U.S. patent application number 17/449384 was filed with the patent office on 2022-01-20 for link failure recovery method and apparatus.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Kunpeng LIU, Di ZHANG.
Application Number | 20220022274 17/449384 |
Document ID | / |
Family ID | 1000005887171 |
Filed Date | 2022-01-20 |
United States Patent
Application |
20220022274 |
Kind Code |
A1 |
ZHANG; Di ; et al. |
January 20, 2022 |
LINK FAILURE RECOVERY METHOD AND APPARATUS
Abstract
This application provides a link failure recovery method and
apparatus. When a link failure occurs and link recovery is
performed, if a terminal device determines that no new link is
identified, according to the method, the terminal device may
report, to a network device, an identifier of a cell in which the
link failure occurs and information indicating whether a new link
is identified for each cell. The network device may reconfigure a
new resource set based on the information, and notify the terminal
device of the new resource set by using downlink control
information DCI. In other words, a reference signal in another
resource set is triggered by using the DCI, and the reference
signal in the resource set is reported for link recovery.
Inventors: |
ZHANG; Di; (Shenzhen,
CN) ; LIU; Kunpeng; (Beijing, CN) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
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CN |
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Family ID: |
1000005887171 |
Appl. No.: |
17/449384 |
Filed: |
September 29, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/CN2020/083104 |
Apr 3, 2020 |
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17449384 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 76/19 20180201;
H04L 5/0048 20130101 |
International
Class: |
H04W 76/19 20060101
H04W076/19; H04L 5/00 20060101 H04L005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2019 |
CN |
201910286536.7 |
Claims
1. A link failure recovery method, comprising: determining that a
link failure occurs in L first cells; and sending a first request
message comprising first indication information to indicate cell
information of the L first cells, L.gtoreq.1, and L is an integer,
wherein the first indication information comprises at least one of
a first part of content or a second part of content, wherein the
first part of content is to indicate cell identifiers of the L
first cells, and wherein the second part of content is to indicate
whether there is no first reference signal that satisfies a first
preset condition.
2. The method according to claim 1, wherein the second part of
content is to indicate whether each of the L first cells has no
first reference signal that satisfies the first preset condition;
or the second part of content is to indicate whether all of the L
first cells have no first reference signal that satisfies the first
preset condition.
3. The method according to claim 1, further comprising: sending a
second request message comprising second indication information to
indicate information about a reference signal for recovering the L
first cells.
4. The method according to claim 3, wherein, in response to the
second part of content indicates a first state in which each of the
L first cells has no first reference signal that satisfies the
first preset condition, the second request message is not sent.
5. A link failure recovery method, comprising: receiving a first
request message comprising first indication information to indicate
cell information of L first cells in which a link failure occurs,
L.gtoreq.1, and L is an integer, wherein the first indication
information comprises at least one of a first part of content or a
second part of content, wherein the first part of content is to
indicate cell identifiers of the L first cells, and wherein the
second part of content is to indicate whether there is no first
reference signal that satisfies a first preset condition; and
determining the cell information of the L first cells based on the
first request message.
6. The method according to claim 5, wherein the second part of
content is to indicate whether each of the L first cells has no
first reference signal that satisfies the first preset condition;
or the second part of content is to indicate whether all of the L
first cells have no first reference signal that satisfies the first
preset condition.
7. The method according to claim 5, further comprising: receiving a
second request message comprising second indication information to
indicate information about a reference signal for recovering the L
first cells.
8. The method according to claim 7, wherein, in response to the
second part of content indicates a first state in which each of the
L first cells has no first reference signal that satisfies the
first preset condition, the second request message is not
received.
9. A link failure recovery apparatus, comprising: a processor,
configured to determine that a link failure occurs in L first
cells; and a transceiver, configured to send a first request
message comprising first indication information to indicate cell
information of the L first cells, L.gtoreq.1, and L is an integer,
wherein the first indication information comprises at least one of
a first part of content or a second part of content, wherein the
first part of content is to indicate cell identifiers of the L
first cells, and wherein the second part of content is to indicate
whether there is no first reference signal that satisfies a first
preset condition.
10. The apparatus according to claim 9, wherein the second part of
content is to indicate whether each of the L first cells has no
first reference signal that satisfies the first preset condition;
or the second part of content is to indicate whether all of the L
first cells have no first reference signal that satisfies the first
preset condition.
11. The apparatus according to claim 9, wherein the transceiver is
further configured to: send a second request message comprising
second indication information to indicate information about a
reference signal for recovering the L first cells.
12. The apparatus according to claim 11, wherein, response to the
second part of content indicates a first state in which each of the
L first cells has no first reference signal that satisfies the
first preset condition, the second request message is not sent.
13. A link failure recovery apparatus, comprising: a transceiver,
configured to receive a first request message comprising first
indication information to indicate cell information of L first
cells, the L cells are cells in which a link failure occurs,
L.gtoreq.1, and L is an integer, wherein the first indication
information comprises at least one of a first part of content or a
second part of content, wherein the first part of content is to
indicate cell identifiers of the L first cells, and wherein the
second part of content is to indicate whether there is no first
reference signal that satisfies a first preset condition; and a
processor, configured to determine the cell information of the L
first cells based on the first request message.
14. The apparatus according to claim 13, wherein the second part of
content is to indicate whether each of the L first cells has no
first reference signal that satisfies the first preset condition;
or the second part of content is to indicate whether all of the L
first cells have no first reference signal that satisfies the first
preset condition.
15. The apparatus according to claim 13, wherein the transceiver is
further configured to: send a second request message comprising
second indication information to indicate information about a
reference signal for recovering the L first cells.
16. The apparatus according to claim 15, wherein, in response to
the second part of content indicates a first state in which each of
the L first cells has no first reference signal that satisfies the
first preset condition, the transceiver does not send the second
request message.
17. A computer-readable storage medium, wherein the
computer-readable storage medium stores a computer program; and
when the computer program is executed, the method according to
claim 1 is implemented.
18. A computer-readable storage medium, wherein the
computer-readable storage medium stores a computer program; and
when the computer program is executed, the method according to
claim 5 is implemented.
19. A chip system, wherein the chip system comprises: a memory,
configured to store instructions; and a processor, configured to:
invoke the instructions from the memory and run the instructions,
to enable a communications device onto which the chip system is
installed to perform the method according to claim 1.
20. A chip system, wherein the chip system comprises: a memory,
configured to store instructions; and a processor, configured to:
invoke the instructions from the memory and run the instructions,
to enable a communications device onto which the chip system is
installed to perform the method according to claim 5.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/CN2020/083104, filed on Apr. 3, 2020, which
claims priority to Chinese Patent Application No. 201910286536.7,
filed on Apr. 10, 2019. The disclosures of the aforementioned
applications are hereby incorporated by reference in their
entireties.
TECHNICAL FIELD
[0002] This application relates to the communications field, and
more specifically, to a link failure recovery method and apparatus
in the communications field.
BACKGROUND
[0003] In a process of communication between a terminal device and
a network device, the terminal device needs to detect an available
beam, and transmit information about the available beam to the
network device, to establish a link connection. When detecting a
link fault (beam failure), the terminal device may send a beam
failure recovery request (BFRQ) message to the network device, to
notify the network device of the link failure, and report
information about a detected new available beam to the network
device. The network device sends a beam failure recovery response
(BFRR) message to the terminal device, to indicate new link
information to the terminal device, so that the terminal device can
establish a new link connection to the network device, thereby
recovering a link.
[0004] If the terminal device cannot determine a new link or cannot
find an available beam, link failure recovery fails. Consequently,
link communication is interrupted, and communication efficiency is
reduced.
SUMMARY
[0005] This application provides a link failure recovery method and
apparatus. The method can increase a link failure recovery
probability, reduce a link failure recovery delay, and improve link
failure recovery reliability.
[0006] According to a first aspect, a link failure recovery method
is provided. The link failure recovery method includes: determining
that M first cells in which a link failure occurs are in a first
state, where the first state is a state in which each of the M
first cells has no first reference signal that satisfies a first
preset condition, M.gtoreq.1, and M is an integer; sending a first
request message on a first resource, where the first request
message is used to indicate cell information of the M first cells;
receiving a response message of the first request message on a
second resource, where the response message of the first request
message is used to indicate a second reference signal resource set,
the second reference signal resource set includes resources of N
second reference signals used to recover the M first cells,
N.gtoreq.1, and N is an integer; and determining the second
reference signal resource set based on the response message of the
first request message.
[0007] Specifically, in this application, a terminal device detects
a current link, and determines that a link failure occurs in L
first cells. The L first cells include a first cell for which a new
link is identified and M first cells for which no new link is
identified. In other words, each of the M first cells has no new
link. L.gtoreq.M.gtoreq.1, and L and M are integers. That is, in
this application, the first request information is used to indicate
that no new link is identified for each of the M first cells in
which the link failure occurs. The first state is a state in which
no new link is identified for each of the M first cells.
[0008] It should be understood that, the resources of the N second
reference signals may be used to recover links of all the M cells,
or used to recover links of some of the M cells. This is not
limited in this application.
[0009] In one embodiment, there may be a plurality of types of
response messages of the first request message. The first type is
as follows: When the first request message indicates a new link for
a first cell with a new link, the response information of the first
request message is information sent on a third resource based on
the new link (which may be a PDCCH sent by using the new link).
[0010] The second type is as follows: For a first cell without a
new link, the response message of the first request message may
indicate an aperiodic/periodic/semi-periodic reference signal
resource set (the second reference signal resource set) or the
like. Alternatively, the response message of the first request
message is associated with a default reference signal resource set
(for example, a reference signal resource set used for beam
management BM, a reference signal resource set used for RRM
measurement, or a reference signal resource set that uses another
function). The reference signal resource set used for beam
management (BM) may be a reference signal resource set with a
repetition identifier being "off" (or may be a reference signal
resource set with a repetition identifier being "on").
[0011] It should be understood that, in this embodiment, the
response message of the first request message mainly refers to the
second type.
[0012] It should be further understood that, that the response
message of the first request message is used to indicate a second
reference signal resource set may be that the response message of
the first request message explicitly indicates the second reference
signal resource set. For example, the response message of the first
request message is configured by using higher layer signaling to be
associated with a reference signal resource set. Alternatively, the
response message of the first request message may implicitly
indicate the second reference signal resource set. For example, the
response message of the first request message is associated with a
reference signal resource set by default. The reference signal
resource set may be a reference signal resource set used for beam
management BM, or may be a reference signal resource set used for
RRM measurement, or may be a reference signal resource set that
uses another function. The default reference signal resource set
may be a reference signal resource set that uses another function,
or may be a reference signal resource set predefined in a protocol.
The second reference signal corresponding to the second reference
signal resource set may be a CSI-RS, a TRS, an SSB, or the
like.
[0013] In one embodiment, the terminal device reports, on an uplink
resource (which may be a PUSCH) indicated by the response message
of the first request message, information about some second
reference signals in the second reference signal resource set.
[0014] It should be understood that, the first request message may
be sent by using one or more request messages. This is not limited
in this embodiment. In addition, the first request message may be a
link failure request message (BFRQ), scheduling request
information, or a combination of the two. This is not limited in
this application. The first request message may alternatively be
carried on one or more first resources. This is not limited in this
embodiment. The first request message may further indicate that the
link failure occurs in the M first cells.
[0015] In addition, the first resource and the second resource may
be resources of a second cell. For example, the first cell may be
an SCell, and the second cell may be a PCell.
[0016] It should be further understood that, in this application,
the first preset condition may be that channel qualify of a
reference signal is greater than or equal to a first preset
threshold. In other words, that there is no first reference signal
that satisfies the first preset condition may further include any
one of the following cases: (1) No first reference signal resource
set is configured, but the first preset threshold is configured.
(2) A first reference signal resource set is configured, but the
first preset threshold is not configured. (3) A first reference
signal resource set and the first preset threshold are configured,
but a first reference signal greater than the first preset
threshold is not identified or does not exist. (4) Neither a first
reference signal resource set nor the first preset threshold is
configured. The first reference signal resource set may be referred
to as a link failure recovery reference signal resource set, and
the first preset threshold may be referred to as a link recovery
threshold. This is not limited in this application.
[0017] It should be further understood that, the "channel quality"
in this application may be at least one of reference signal
received power (L1-reference signal received power, L1-RSRP), a
signal to interference plus noise ratio (L1-signal to interference
plus noise ratio, L1-SINR), a signal to interference plus noise
ratio (SINR), a channel quality indicator (CQI), and the like.
[0018] In this application, after determining that there is no new
link, the terminal device may detect DCI information in the second
cell (for example, the PCell), to determine a new reference signal
resource set. After determining that there is a new link, the
terminal device may detect response information in the first cell
based on the new link. This application includes but is not limited
to this.
[0019] Based on the foregoing solution, when a link failure occurs
and link recovery is performed, if the terminal device determines
that no new link is identified, the terminal device may report, to
the network device, an identifier of a cell in which the link
failure occurs and information indicating that no new link is
identified for the cell. The network device may reconfigure a new
resource set based on the information, and notify the terminal
device of the new resource set by using the response message of the
first request message. In other words, a reference signal in
another resource set is indicated by using the response message of
the first request message, and the reference signal in the resource
set is reported for link recovery. In this way, a link failure
recovery probability can be increased, a link failure recovery
delay can be reduced, and link failure recovery reliability can be
improved.
[0020] In one embodiment, the cell information of the M first cells
includes cell identifiers of the M first cells and/or information
about the first state of the M first cells.
[0021] It should be understood that, "the cell information of the M
first cells includes cell identifiers of the M first cells and/or
information about the first state of the M first cells" may be
replaced with "the cell information of the M first cells includes
cell identifiers of the M first cells and information about the
first state of the M first cells, or the cell information of the M
first cells includes information about the first state of the M
first cells"; or may be replaced with "the cell information of the
M first cells includes cell identifiers of the M first cells and
information about the first state of the M first cells"; or may be
replaced with "the first request message is used to indicate cell
identifiers of the M first cells and information about the first
state of the M first cells, or the first request message is used to
indicate information about the first state of the M first cells";
or may be replaced with "the first request message is used to
indicate cell identifiers of the M first cells and/or information
about the first state of the M first cells"; or may be replaced
with "the first request message is used to indicate cell
identifiers of the M first cells and information about the first
state of the M first cells".
[0022] It should be understood that, in one embodiment, the cell
information of the M first cells includes only the information
about the first state. That is, the first request message indicates
that the link failure occurs in a first cell (a cell in which the
link failure occurs may not be indicated, and a range of cells in
which the link failure occurs may be indicated, for example, the
link failure occurs in a cell in a first group of cells) and
indicates a state in which no new link can be identified for the
cell in which the link failure occurs. Correspondingly, the network
device may reconfigure some reference signal resources for link
recovery.
[0023] The information about the first state of the M first cells
may be understood as that the M first cells may share one first
state, and the first state indicates that no new link is identified
for all of the M first cells, or may be understood as that each of
the M first cells has one first state (that is, there are M first
states), and a first state corresponding to a cell indicates that
no new link is identified for the first cell.
[0024] In one embodiment, for at least one of the cases (1), (2),
and (4) in which there is no first reference signal that satisfies
the first preset condition, the network device learns that in this
case, the terminal device cannot obtain a first reference signal
that satisfies the first preset condition, that is, the network
device implicitly learns of the first state in this case.
Therefore, the terminal device may only need to (explicitly or
implicitly) report the cell identifiers of the M first cells, and
does not need to report the information about the first state of
the M first cells (in other words, the first request message
implicitly indicates the information about the first state of the M
first cells).
[0025] In one embodiment, for the case (3) in which there is no
first reference signal that satisfies the first preset condition,
the terminal device needs to report at least the information about
the first state of the M first cells, so that the network device
reconfigures or indicates a new reference signal resource set for
link recovery.
[0026] It may be understood that, for the foregoing several cases,
the first request message explicitly or implicitly indicates the
information about the first state of the M first cells.
[0027] For example, the cell information of the M first cells
includes M cell identifiers and the information about the first
state, and the information about the first state may indicate that
no new link is identified for the M SCells.
[0028] Based on the foregoing implementation, the network device
may configure one or more resources for a cell in which a link
failure occurs. The resource is used to carry the first request
message, and the first request message may indicate whether a link
failure occurs in a cell and/or indicate cells in which the link
failure occurs. If the terminal device identifies no new link for
the cell in which the link failure occurs, the first request
message may indicate that no new link is identified for the cell in
which the link failure occurs. If the network device can learn of
the cell in which the link failure occurs and/or a new link
identification status of the cell in which the link failure occurs,
the network device may trigger a new resource set in time based on
a status in which no new link is identified for the cell in which
the link failure occurs, thereby reducing a link failure recovery
delay.
[0029] In one embodiment, after the determining the second
reference signal resource set based on the response message of the
first request message, the method further includes: sending a
second request message. The second request message is used to
indicate information about K second reference signals for
recovering an i.sup.th first cell in the M first cells,
1.ltoreq.i.ltoreq.M, 1.ltoreq.K.ltoreq.N, and i and K are integers;
and/or the second request message is used to indicate information
about the first state of a i.sup.th first cell in the M first
cells, the first state is a state in which there is no second
reference signal that is used to recover the j.sup.th first cell
and that satisfies a second preset threshold, 1.ltoreq.j.ltoreq.M,
and j is an integer.
[0030] It should be understood that, there may be one or more of
the following cases for content indicated by the second request
message:
[0031] (1) The terminal device identifies, from the N second
reference signals, all new links of the M first cells (which may
also be understood as that each of the M first cells has at least
one corresponding new link). In this case, the second request
message may be used to indicate the information about the K second
reference signals for recovering the i.sup.th first cell in the M
first cells, 1.ltoreq.i.ltoreq.M, 1.ltoreq.K.ltoreq.N, i and K are
integers, and i may be any one of 1 to M. It should be understood
that in this case, values of K that correspond to all the cells may
be different.
[0032] (2) The terminal device identifies, from the N second
reference signals, no new link for any one of the M first cells
(which may also be understood as that no corresponding new link is
identified for each of the M first cells). In this case, the second
request message is used to indicate the information about the first
state of the j.sup.th first cell in the M first cells, the first
state is a state in which there is no second reference signal that
is used to recover the j.sup.th first cell and that satisfies the
second preset threshold, 1.ltoreq.j.ltoreq.M, j is an integer, and
j may be any one of 1 to M.
[0033] (3) The terminal device identifies new links of some of the
M first cells, and identifies no new link for the other first cells
in the M first cells from the N second reference signals (which may
also be understood as that new links of some of the M first cells
are identified, and new links of the other cells are not
identified). In this case, the second request message is used to
indicate the information about the K second reference signals for
recovering the i.sup.th first cell in the M first cells,
1.ltoreq.i.ltoreq.M, 1.ltoreq.K.ltoreq.N, and i and K are integers;
and the second request message is further used to indicate the
information about the first state of the i.sup.th first cell in the
M first cells, the first state is a state in which there is no
second reference signal that is used to recover the j.sup.th first
cell and that satisfies the second preset threshold,
1.ltoreq.j.ltoreq.M, and j is an integer. i is not equal to j. That
is, the second request message is used to indicate the information
about the K second reference signals for recovering the i.sup.th
first cell in the M first cells and the information about the first
state of the j.sup.th first cell in the M first cells.
[0034] In one embodiment, the terminal device may send the second
request information on the uplink resource (PUSCH) indicated by the
response information of the first request message.
[0035] In one embodiment, channel quality of each of the K second
reference signals is greater than or equal to the second preset
threshold.
[0036] In one embodiment, the second preset threshold herein may be
the first preset threshold, namely, the link recovery
threshold.
[0037] In one embodiment, the method further includes: receiving a
response message of the second request message on a third resource
based on the information about the K second reference signals.
[0038] In one embodiment, the third resource is a resource of the
first cell. Specifically, the third resource may be a resource of
the SCell. The third resource may be a resource of the i.sup.th
first cell.
[0039] In one embodiment, when a quantity of times that the second
request message indicates that the i.sup.th first cell in the M
first cells is in the first state is greater than or equal to a
preset quantity of times, it is determined that link recovery of
the i.sup.th first cell fails.
[0040] Alternatively, when a total quantity of times that the first
request message and the second request message indicate that the
i.sup.th first cell in the M first cells is in the first state is
greater than or equal to a preset quantity of times, it is
determined that link recovery of the i.sup.th first cell fails,
where 1.ltoreq.i.ltoreq.M, and i is an integer.
[0041] In other words, when a quantity of times that the first
request information and/or the second request information
indicate/indicates that the i.sup.th first cell in the M first
cells is in the first state is equal to the preset quantity of
times, and the response information of the second request
information is not received, it is determined that the link
recovery of the i.sup.th first cell fails. Specifically, when a
quantity of times that the terminal device reports, for one or more
times by using the second request message, that there is no new
link (no new beam) reaches the preset quantity of times, but the
response information of the second request information is not
received, it is determined that the link recovery of the i.sup.th
first cell fails.
[0042] Alternatively, when a quantity of times that the first
request information and/or the second request information
indicate/indicates that the i.sup.th first cell in the M first
cells is in the first state is equal to the preset quantity of
times, and the response information of the second request
information is not received, the second request information of the
i.sup.th first cell is not sent. Specifically, when a quantity of
times that the terminal device reports, for one or more times by
using the first request message and/or the second request message,
that there is no new link (no new beam) reaches the preset quantity
of times, but the response information of the second request
information is not received, the second request message not be
repeatedly sent, and it is considered by default that the link
recovery fails.
[0043] In one embodiment, the response message of the first request
message is any one of the following: downlink control information
DCI in a dedicated search space; DCI in a dedicated control
resource set; DCI scrambled by using a dedicated radio network
temporary identifier RNTI; or DCI including a preset state
value.
[0044] According to a second aspect, a link failure recovery method
is provided. The link failure recovery method includes: receiving a
first request message on a first resource, where the first request
message is used to indicate cell information of M first cells in
which a link failure occurs, the M first cells are in a first
state, the first state is a state in which each of the M first
cells has no first reference signal that satisfies a first preset
condition, M.gtoreq.1, and M is an integer; determining the cell
information of the M first cells based on the first request
message; and sending a response message of the first request
message on a second resource, where the response message of the
first request message is used to indicate a second reference signal
resource set, the second reference signal resource set includes
resources of N second reference signals used to recover the M first
cells, N.gtoreq.1, and N is an integer.
[0045] In one embodiment, the cell information of the M first cells
includes cell identifiers of the M first cells and/or information
about the first state of the M first cells.
[0046] In one embodiment, after the sending a response message of
the first request message on a second resource, the method further
includes: receiving a second request message, where the second
request message is used to indicate information about K second
reference signals for recovering an i.sup.th first cell in the M
first cells, 1.ltoreq.i.ltoreq.M, 1.ltoreq.K.ltoreq.N, and i and K
are integers; and/or the second request message is used to indicate
information about the first state of a j.sup.th first cell in the M
first cells, the first state is a state in which there is no second
reference signal that is used to recover the j.sup.th first cell
and that satisfies a second preset threshold, 1.ltoreq.j.ltoreq.M,
and j is an integer. With reference to the second aspect and the
foregoing implementations, In one embodiment, channel quality of
each of the K second reference signals is greater than or equal to
the second preset threshold.
[0047] In one embodiment, the method further includes: sending a
response message of the second request message on a third resource
based on the information about the K second reference signals.
[0048] In one embodiment, when a quantity of times that the second
request message indicates that the i.sup.th first cell in the M
first cells is in the first state is greater than or equal to a
preset quantity of times, it is determined that link recovery of
the i.sup.th first cell fails.
[0049] In one embodiment, the response message of the first request
message is any one of the following: downlink control information
DCI in a dedicated search space; DCI in a dedicated control
resource set; DCI scrambled by using a dedicated radio network
temporary identifier RNTI; or DCI including a preset state
value.
[0050] According to a third aspect, a link failure recovery method
is provided. The link failure recovery method includes: determining
that a link failure occurs in L first cells; and sending a first
request message, where the first request message includes first
indication information, the first indication information is used to
indicate cell information of the L first cells, L.gtoreq.1, and L
is an integer, where the first indication information includes a
first part of content and/or a second part of content, the first
part of content is used to indicate cell identifiers of the L first
cells, and the second part of content is used to indicate whether
there is no first reference signal that satisfies a first preset
condition.
[0051] For example, in this application, a terminal device detects
a current link, and determines that a link failure occurs in L
SCells. The L SCells include an SCell for which a new link is
identified and M SCells for which no new link is identified. In
other words, each of the M SCells has no new link.
L.gtoreq.M.gtoreq.1, and L and M are integers.
[0052] Based on the foregoing embodiments, a network device may
configure one or more resources for the terminal device. The
resource is used to carry the first indication information, and the
first indication information may indicate whether a link failure
occurs in one or more cells, or indicate a cell identifier of one
or more cells in which a link failure occurs, and indicate a new
link identification status of each of the one or more cells
(whether a new link is identified). The terminal device reports the
first indication information to the network device. If the network
device can learn of the cell in which the link failure occurs and
the new link identification status of the cell, the network device
may trigger a new reference signal resource set in time based on
the new link identification status of each cell in which the link
failure occurs, thereby reducing a link failure recovery delay.
[0053] In one embodiment, the second part of content is used to
indicate whether each of the L first cells has no first reference
signal that satisfies the first preset condition; or the second
part of content is used to indicate whether all of the L first
cells have no first reference signal that satisfies the first
preset condition.
[0054] Alternatively, it may be described as follows: The second
part of content is used to indicate whether each of the L first
cells has a first reference signal that satisfies the first preset
condition; or the second part of content is used to indicate
whether all of the L first cells have a first reference signal that
satisfies the first preset condition; or the second part of content
is used to indicate that at least one of the L first cells has a
first reference signal that satisfies the first preset
condition.
[0055] In one embodiment, the method further includes: sending a
second request message, where the second request message includes
second indication information, and the second indication
information is used to indicate information about a reference
signal for recovering the L first cells.
[0056] Alternatively, the second request message is used to
indicate information about a reference signal for recovering the L
first cells.
[0057] In one embodiment, that the second request message is used
to indicate information about a reference signal for recovering the
L first cells includes: The second request message is used to
indicate information about a first state or a reference signal for
recovering each of the L first cells.
[0058] It should be understood that, when the second part of
content is used to indicate that at least one of the L first cells
has a first reference signal that satisfies the first preset
condition, the second request message indicates information about
the reference signal that satisfies the first preset condition and
information about a state in which the first preset condition is
not satisfied. It may also be understood that the second request
message indicates information about reference signals corresponding
to cells for which a new link is identified, and the first state of
a cell for which no new link is identified. In one embodiment, the
first indication information and the second indication information
are independently encoded.
[0059] In one embodiment, the first request message and the second
request message are a same request message or different request
messages. In other words, the first indication information and the
second indication information may be sent by using a same link
failure request message or different link failure request
messages.
[0060] It should be understood that, in this embodiment of this
application, the first request message and the second request
message may be same request information, for example, are
collectively referred to as the first request message. In this
case, "not sending the second request message" may be understood as
"not sending the second indication information"; or may be
understood as that the first request message does not include the
second indication information; or may be understood as that the
first request message includes only the first indication
information.
[0061] In one embodiment, the first indication information and the
second indication information are carried on a same channel, or
carried on different channels.
[0062] In one embodiment, when the second part of content indicates
a first state, the second request message is not sent, and the
first state is a state in which each of the L first cells has no
first reference signal that satisfies the first preset
condition.
[0063] It should be understood that, in this implementation, when
the second part of content indicates that each of the L first cells
in which the link failure occurs has no new link, the terminal
device may not generate the second request message or send the
second request message, because no new link information needs to be
reported to the network device.
[0064] It should be further understood that, the second part of
content may indicate that some cells are in the first state, and
the other cells are in a second state. The corresponding second
indication information includes a part of information about the
first reference signal and a part of information about the second
reference signal.
[0065] In one embodiment, when the second part of content indicates
the first state of an i.sup.th first cell in the L first cells, the
second indication information indicates information about a second
reference signal for recovering the i.sup.th first cell, the first
state is a state in which the i.sup.th first cell in the L first
cells has no first reference signal that satisfies the first preset
condition, 1.ltoreq.i.ltoreq.L, and i is an integer.
[0066] In one embodiment, when the second part of content indicates
a second state of a j.sup.th first cell in the L first cells, the
second indication information is used to indicate information about
a first reference signal for recovering the j.sup.th first cell,
the second state is a state in which the j.sup.th first cell in the
L first cells has a first reference signal that satisfies the first
preset condition, 1.ltoreq.j.ltoreq.L, and j is an integer.
[0067] It should be understood that, In one embodiment, based on
different states indicated by the second part of content, there may
be one or more of the following cases for content indicated by the
second request message:
[0068] (1) The terminal device identifies no new link for any one
of the L first cells. That is, when the second part of content
indicates that all of the L first cells are in the first state, the
second indication information indicates the information about the
second reference signal for recovering the L first cells, the first
state is a state in which the i.sup.th first cell in the L first
cells has no first reference signal that satisfies the first preset
condition, 1.ltoreq.i.ltoreq.L, i is an integer, and i may be any
one of 1 to L.
[0069] (2) The terminal device identifies a new link of any one of
the L first cells. That is, when the second part of content
indicates that all of the L first cells are in the second state,
the second indication information indicates the information about
the first reference signal for recovering the L first cells, the
second state is a state in which the j.sup.th first cell in the L
first cells has a first reference signal that satisfies the first
preset condition, 1.ltoreq.j.ltoreq.L, j is an integer, and j may
be any one of 1 to L.
[0070] (3) The terminal device identifies new links of some of the
M first cells, and identifies no new link for the other first cells
in the M first cells from N second reference signals (which may
also be understood as that new links of some of the M first cells
are identified, and new links of the other cells are not
identified). That is, when the second part of content indicates the
first state of the i.sup.th first cell in the L first cells and the
second state of the j.sup.th first cell in the L first cells, the
second indication information indicates the information about the
second reference signal for recovering the i.sup.th first cell and
the information about the first reference signal for recovering the
j.sup.th first cell, 1.ltoreq.j.ltoreq.L, 1.ltoreq.i.ltoreq.L, i is
not equal to j, and i and j are integers.
[0071] In one embodiment, a w.sup.th reference signal indicated by
the second indication information corresponds to a w.sup.th cell in
the L first cells indicated by the first part of content,
1.ltoreq.i.ltoreq.L, and w is an integer.
[0072] In one embodiment, the method further includes: detecting,
based on an i.sup.th reference signal indicated by the second
indication information, response information of the i.sup.th cell
in the L first cells indicated by the first part of content, where
1.ltoreq.i.ltoreq.L, and i is an integer.
[0073] It should be understood that, the "first request message" in
the third aspect may be different from the "first request message"
in the first aspect, and the "second request message" in the third
aspect may be different from the "second request message" in the
first aspect.
[0074] According to a fourth aspect, a link failure recovery method
is provided. The link failure recovery method includes: receiving a
first request message, where the first request message includes
first indication information, the first indication information is
used to indicate cell information of L first cells, the L first
cells are cells in which a link failure occurs, L.gtoreq.1, and L
is an integer, where the first indication information includes a
first part of content and/or a second part of content, the first
part of content is used to indicate cell identifiers of the L first
cells, and the second part of content is used to indicate whether
there is no first reference signal that satisfies a first preset
condition; and determining the cell information of the L first
cells based on the first request message.
[0075] In one embodiment, the second part of content is used to
indicate whether each of the L first cells has no first reference
signal that satisfies the first preset condition; or the second
part of content is used to indicate whether all of the L first
cells have no first reference signal that satisfies the first
preset condition.
[0076] In one embodiment, the method further includes: sending a
second request message, where the second request message includes
second indication information, and the second indication
information is used to indicate information about a reference
signal for recovering the L first cells.
[0077] In one embodiment, the first indication information and the
second indication information are independently encoded.
[0078] In one embodiment, the first indication information and the
second indication information are carried on a same channel, or
carried on different channels.
[0079] In one embodiment, when the second part of content indicates
a first state, the second request message is not sent, and the
first state is a state in which each of the L first cells has no
first reference signal that satisfies the first preset
condition.
[0080] In one embodiment, when the second part of content indicates
a first state of an i.sup.th first cell in the L first cells, the
second indication information indicates information about a second
reference signal for recovering the i.sup.th first cell, the first
state is a state in which the i.sup.th first cell in the L first
cells has no first reference signal that satisfies the first preset
condition, 1.ltoreq.i.ltoreq.L, and i is an integer.
[0081] In one embodiment, when the second part of content indicates
a second state of a j.sup.th first cell in the L first cells, the
second indication information is used to indicate information about
a first reference signal for recovering the j.sup.th first cell,
the second state is a state in which the j.sup.th first cell in the
L first cells has a first reference signal that satisfies the first
preset condition, 1.ltoreq.j.ltoreq.L, and j is an integer.
[0082] In one embodiment, an i.sup.th reference signal indicated by
the second indication information corresponds to the i.sup.th cell
in the L first cells indicated by the first part of content,
1.ltoreq.i.ltoreq.L, and i is an integer.
[0083] It should be understood that, for the solutions described in
this application, the "first request message" in the fourth aspect
may be different from the "first request message" in the second
aspect, and the "second request message" in the fourth aspect may
be different from the "second request message" in the second
aspect.
[0084] According to a fifth aspect, a link failure recovery method
is provided. The link failure recovery method includes: determining
that M first cells are in a first state, where the first state is a
state in which each of the M first cells has no first reference
signal that satisfies a first preset condition; sending a first
request message on a first resource, where the first request
message is used to indicate cell information of the M first cells,
M.gtoreq.1, and M is an integer; and receiving a response message
of the first request message, where the response message of the
first request message is used to indicate quasi-colocation
(quasi-colocation, QCL) assumption information of at least one of
the M first cells.
[0085] In one embodiment, after the response message of the first
request message is received, timing of a link failure recovery
clock is stopped.
[0086] It should be understood that, the first aspect and the fifth
aspect may be combined with the third aspect, that is, the first
aspect and the second aspect may be a part of the third aspect.
[0087] According to a sixth aspect, a link failure recovery method
is provided. The link failure recovery method includes: receiving a
first request message on a first resource, where the first request
message is used to indicate cell information of M first cells in
which a link failure occurs, the M first cells are in a first
state, the first state is a state in which each of the M first
cells has no first reference signal that satisfies a first preset
condition, M.gtoreq.1, and M is an integer; and sending a response
message of the first request message, where the response message of
the first request message is used to indicate QCL information of at
least one of the M first cells.
[0088] In one embodiment, the response message of the first request
message is a transmission configuration indicator (transmission
configuration indicator, TCI).
[0089] It should be understood that, the second aspect and the
sixth aspect may be combined with the fourth aspect, that is, the
second aspect and the sixth aspect may be a part of the fourth
aspect.
[0090] According to a seventh aspect, a link failure recovery
apparatus is provided. The link failure recovery apparatus
includes: a processing unit, configured to determine that M first
cells in which a link failure occurs are in a first state, where
the first state is a state in which each of the M first cells has
no first reference signal that satisfies a first preset condition,
M.gtoreq.1, and M is an integer; and a communications unit,
configured to send a first request message on a first resource,
where the first request message is used to indicate cell
information of the M first cells, where the communications unit is
further configured to receive a response message of the first
request message on a second resource, where the response message of
the first request message is used to indicate a second reference
signal resource set, the second reference signal resource set
includes resources of N second reference signals used to recover
the M first cells, N.gtoreq.1, and N is an integer; and the
processing unit is further configured to determine the second
reference signal resource set based on the response message of the
first request message.
[0091] In one embodiment, the cell information of the M first cells
includes cell identifiers of the M first cells and/or information
about the first state of the M first cells.
[0092] In one embodiment, the communications unit is further
configured to send a second request message, where the second
request message is used to indicate information about K second
reference signals for recovering an i.sup.th first cell in the M
first cells, 1.ltoreq.i.ltoreq.M, 1.ltoreq.K.ltoreq.N, and i and K
are integers; and/or the second request message is used to indicate
information about the first state of a j.sup.th first cell in the M
first cells, the first state is a state in which there is no second
reference signal that is used to recover the i.sup.th first cell
and that satisfies a second preset threshold, 1.ltoreq.j.ltoreq.M,
and j is an integer.
[0093] In one embodiment, channel quality of each of the K second
reference signals is greater than or equal to the second preset
threshold.
[0094] In one embodiment, the communications unit is further
configured to receive a response message of the second request
message on a third resource based on the information about the K
second reference signals.
[0095] In one embodiment, when a quantity of times that the second
request message indicates that the i.sup.th first cell in the M
first cells is in the first state is greater than or equal to a
preset quantity of times, it is determined that link recovery of
the i.sup.th first cell fails, where 1.ltoreq.i.ltoreq.M, and i is
an integer.
[0096] In one embodiment, the response message of the first request
message is any one of the following: downlink control information
DCI in a dedicated search space; DCI in a dedicated control
resource set; DCI scrambled by using a dedicated radio network
temporary identifier RNTI; or DCI including a preset state
value.
[0097] According to an eighth aspect, a link failure recovery
apparatus is provided. The link failure recovery apparatus
includes: a communications unit, configured to receive a first
request message on a first resource, where the first request
message is used to indicate cell information of M first cells in
which a link failure occurs, the M first cells are in a first
state, the first state is a state in which each of the M first
cells has no first reference signal that satisfies a first preset
condition, M.gtoreq.1, and M is an integer; and a processing unit,
configured to determine the cell information of the M first cells
based on the first request message, where the communications unit
is further configured to send a response message of the first
request message on a second resource, where the response message of
the first request message is used to indicate a second reference
signal resource set, the second reference signal resource set
includes resources of N second reference signals used to recover
the M first cells, N.gtoreq.1, and N is an integer.
[0098] In one embodiment, the cell information of the M first cells
includes cell identifiers of the M first cells and/or information
about the first state of the M first cells.
[0099] In one embodiment, the communications unit is further
configured to receive a second request message, where the second
request message is used to indicate information about K second
reference signals for recovering an i.sup.th first cell in the M
first cells, 1.ltoreq.i.ltoreq.M, 1.ltoreq.K.ltoreq.N, and i and K
are integers; and/or the second request message is used to indicate
information about the first state of a j.sup.th first cell in the M
first cells, the first state is a state in which there is no second
reference signal that is used to recover the i.sup.th first cell
and that satisfies a second preset threshold, 1.ltoreq.j.ltoreq.M,
and j is an integer.
[0100] In one embodiment, channel quality of each of the K second
reference signals is greater than or equal to the second preset
threshold.
[0101] In one embodiment, the communications unit is further
configured to send a response message of the second request message
on a third resource based on the information about the K second
reference signals.
[0102] In one embodiment, when a quantity of times that the second
request message indicates that the i.sup.th first cell in the M
first cells is in the first state is greater than or equal to a
preset quantity of times, it is determined that link recovery of
the i.sup.th first cell fails.
[0103] In one embodiment, the response message of the first request
message is any one of the following: downlink control information
DCI in a dedicated search space; DCI in a dedicated control
resource set; DCI scrambled by using a dedicated radio network
temporary identifier RNTI; or DCI including a preset state
value.
[0104] According to a ninth aspect, a link failure recovery method
is provided. The link failure recovery apparatus includes:
determining that a link failure occurs in L cells; and sending a
first request message, where the first request message includes
first indication information, the first indication information is
used to indicate cell information of the L first cells, L.gtoreq.1,
and L is an integer, where the first indication information
includes a first part of content and/or a second part of content,
the first part of content is used to indicate cell identifiers of
the L first cells, and the second part of content is used to
indicate whether there is no first reference signal that satisfies
a first preset condition.
[0105] In one embodiment, the second part of content is used to
indicate whether each of the L first cells has no first reference
signal that satisfies the first preset condition; or the second
part of content is used to indicate whether all of the L first
cells have no first reference signal that satisfies the first
preset condition.
[0106] In one embodiment, the method further includes: sending a
second request message, where the second request message includes
second indication information, and the second indication
information is used to indicate information about a reference
signal for recovering the L first cells.
[0107] In one embodiment, the first indication information and the
second indication information are independently encoded.
[0108] In one embodiment, the first indication information and the
second indication information are carried on a same channel, or
carried on different channels.
[0109] In one embodiment, when the second part of content indicates
a first state, the second request message is not sent, and the
first state is a state in which each of the L first cells has no
first reference signal that satisfies the first preset
condition.
[0110] In one embodiment, when the second part of content indicates
the first state of an i.sup.th first cell in the L first cells, the
second indication information indicates information about a second
reference signal for recovering the i.sup.th first cell, the first
state is a state in which the i.sup.th first cell in the L first
cells has no first reference signal that satisfies the first preset
condition, 1.ltoreq.i.ltoreq.L, and i is an integer.
[0111] In one embodiment, when the second part of content indicates
a second state of a j.sup.th first cell in the L first cells, the
second indication information is used to indicate information about
a first reference signal for recovering the j.sup.th first cell,
the second state is a state in which the j.sup.th first cell in the
L first cells has a first reference signal that satisfies the first
preset condition, 1.ltoreq.j.ltoreq.L, and j is an integer.
[0112] In one embodiment, an i.sup.th reference signal indicated by
the second indication information corresponds to the i.sup.th cell
in the L first cells indicated by the first part of content,
1.ltoreq.i.ltoreq.L, and i is an integer. It should be understood
that, the "first request message" in the ninth aspect may be
different from the "first request message" in the seventh aspect,
and the "second request message" in the ninth aspect may be
different from the "second request message" in the seventh
aspect.
[0113] According to a tenth aspect, a link failure recovery
apparatus is provided. The link failure recovery apparatus
includes: a communications unit, configured to receive a first
request message, where the first request message includes first
indication information, the first indication information is used to
indicate cell information of L first cells, the L cells are cells
in which a link failure occurs, L.gtoreq.1, and L is an integer,
where the first indication information includes a first part of
content and/or a second part of content, the first part of content
is used to indicate cell identifiers of the L first cells, and the
second part of content is used to indicate whether there is no
first reference signal that satisfies a first preset condition; and
a processing unit, configured to determine the cell information of
the L first cells based on the first request message.
[0114] In one embodiment, the second part of content is used to
indicate whether each of the L first cells has no first reference
signal that satisfies the first preset condition; or the second
part of content is used to indicate whether all of the L first
cells have no first reference signal that satisfies the first
preset condition.
[0115] In one embodiment, the communications unit is further
configured to send a second request message, where the second
request message includes second indication information, and the
second indication information is used to indicate information about
a reference signal for recovering the L first cells.
[0116] In one embodiment, the first indication information and the
second indication information are independently encoded.
[0117] In one embodiment, the first indication information and the
second indication information are carried on a same channel, or
carried on different channels.
[0118] In one embodiment, when the second part of content indicates
a first state, the communications unit does not send the second
request message, and the first state is a state in which each of
the L first cells has no first reference signal that satisfies the
first preset condition.
[0119] In one embodiment, when the second part of content indicates
the first state of an i.sup.th first cell in the L first cells, the
second indication information indicates information about a second
reference signal for recovering the i.sup.th first cell, the first
state is a state in which the i.sup.th first cell in the L first
cells has no first reference signal that satisfies the first preset
condition, 1.ltoreq.i.ltoreq.L, and i is an integer.
[0120] In one embodiment, when the second part of content indicates
a second state of a j.sup.th first cell in the L first cells, the
second indication information is used to indicate information about
a first reference signal for recovering the j.sup.th first cell,
the second state is a state in which the j.sup.th first cell in the
L first cells has a first reference signal that satisfies the first
preset condition, 1.ltoreq.j.ltoreq.L, and j is an integer.
[0121] In one embodiment, an i.sup.th reference signal indicated by
the second indication information corresponds to the i.sup.th cell
in the L first cells indicated by the first part of content,
1.ltoreq.i.ltoreq.L, and i is an integer.
[0122] It should be understood that, the "first request message" in
the tenth aspect may be different from the "first request message"
in the eighth aspect, and the "second request message" in the tenth
aspect may be different from the "second request message" in the
eighth aspect.
[0123] According to an eleventh aspect, a link failure recovery
apparatus is provided. The link failure recovery apparatus
includes: a processing unit, configured to determine that M first
cells are in a first state, where the first state is a state in
which each of the M first cells has no first reference signal that
satisfies a first preset condition; and a communications unit,
configured to send a first request message on a first resource,
where the first request message is used to indicate cell
information of the M first cells, M.gtoreq.1, and M is an integer,
where the communications unit is further configured to receive a
response message of the first request message, where the response
message of the first request message is used to indicate
quasi-colocation (quasi-colocation, QCL) assumption information of
at least one of the M first cells.
[0124] In one embodiment, the processing unit is further configured
to: after the response message of the first request message is
received, stop timing of a link failure recovery clock.
[0125] According to a twelfth aspect, a link failure recovery
apparatus is provided. The link failure recovery apparatus
includes: a communications unit, configured to receive a first
request message on a first resource, where the first request
message is used to indicate cell information of M first cells in
which a link failure occurs, the M first cells are in a first
state, the first state is a state in which each of the M first
cells has no first reference signal that satisfies a first preset
condition, M.gtoreq.1, and M is an integer; and a processing unit,
configured to determine the cell information of the M first cells
based on the first request message, where the communications unit
is further configured to send a response message of the first
request message, where the response message of the first request
message is used to indicate QCL information of at least one of the
M first cells.
[0126] In one embodiment, the response message of the first request
message is a transmission configuration indicator (transmission
configuration indicator, TCI).
[0127] According to a thirteenth aspect, a communications apparatus
is provided. The communications apparatus has functions of
implementing the terminal device in the method designs in the first
aspect, the third aspect, and the fifth aspect. The functions may
be implemented by hardware, or may be implemented by hardware by
executing corresponding software. The hardware or the software
includes one or more units corresponding to the foregoing
functions.
[0128] According to a fourteenth aspect, a communications apparatus
is provided. The communications apparatus has functions of
implementing the network device (for example, a base station) in
the method designs in the second aspect, the fourth aspect, and the
sixth aspect. The functions may be implemented by hardware, or may
be implemented by hardware by executing corresponding software. The
hardware or the software includes one or more units corresponding
to the foregoing functions.
[0129] According to a fifteenth aspect, a terminal device is
provided. The terminal device includes a transceiver and a
processor. In one embodiment, the terminal device further includes
a memory. The processor is configured to control the transceiver to
send and receive a signal. The memory is configured to store a
computer program. The processor is configured to invoke the
computer program from the memory and run the computer program, to
enable the terminal device to perform the method according to any
one of the possible implementations of the first aspect, the third
aspect, and the fifth aspect.
[0130] According to a sixteenth aspect, a network device is
provided. The network device includes a transceiver and a
processor. In one embodiment, the network device further includes a
memory. The processor is configured to control the transceiver to
send and receive a signal. The memory is configured to store a
computer program. The processor is configured to invoke the
computer program from the memory and run the computer program, to
enable the network device to perform the method according to any
one of the possible implementations of the second aspect, the
fourth aspect, and the sixth aspect.
[0131] According to a seventeenth aspect, a communications system
is provided. The system includes the terminal devices in the
seventh aspect, the ninth aspect, and the eleventh aspect, and the
network devices in the eighth aspect, the tenth aspect, and the
twelfth aspect; or the system includes the terminal device in the
fifteenth aspect and the network device in the sixteenth
aspect.
[0132] According to an eighteenth aspect, a communications
apparatus is provided. The communications apparatus may be the
terminal device in the foregoing method designs, or may be a chip
disposed in the terminal device. The communications apparatus
includes a processor that is coupled to a memory and may be
configured to execute instructions in the memory, to implement the
method performed by the terminal device in any one of the possible
implementations of the first aspect, the third aspect, and the
fifth aspect. In one embodiment, the communications apparatus
further includes the memory. In one embodiment, the communications
apparatus further includes a communications interface, and the
processor is coupled to the communications interface.
[0133] When the communications apparatus is the terminal device,
the communications interface may be a transceiver or an
input/output interface.
[0134] When the communications apparatus is the chip disposed in
the terminal device, the communications interface may be an
input/output interface.
[0135] In one embodiment, the transceiver may be a transceiver
circuit. In one embodiment, the input/output interface may be an
input/output circuit.
[0136] According to a nineteenth aspect, a communications apparatus
is provided. The communications apparatus may be the network device
in the foregoing method designs, or may be a chip disposed in the
network device. The communications apparatus includes a processor
that is coupled to a memory and may be configured to execute
instructions in the memory, to implement the method performed by
the network device in any one of the possible implementations of
the second aspect, the fourth aspect, and the sixth aspect. In one
embodiment, the communications apparatus further includes the
memory. In one embodiment, the communications apparatus further
includes a communications interface, and the processor is coupled
to the communications interface.
[0137] When the communications apparatus is the network device, the
communications interface may be a transceiver or an input/output
interface.
[0138] When the communications apparatus is the chip disposed in
the network device, the communications interface may be an
input/output interface.
[0139] In one embodiment, the transceiver may be a transceiver
circuit. In one embodiment, the input/output interface may be an
input/output circuit.
[0140] According to a twentieth aspect, a computer program product
is provided. The computer program product includes computer program
code, and when the computer program code is run on a computer, the
computer is enabled to perform the methods according to the
foregoing aspects.
[0141] According to a twenty-first aspect, a computer-readable
medium is provided. The computer-readable medium stores program
code, and when the computer program code is run on a computer, the
computer is enabled to perform the methods according to the
foregoing aspects.
BRIEF DESCRIPTION OF DRAWINGS
[0142] FIG. 1 is a schematic architectural diagram of a mobile
communications system to which an embodiment of this application is
applicable;
[0143] FIG. 2 is a schematic flowchart of a link failure recovery
method;
[0144] FIG. 3 is a schematic flowchart of an example of a link
failure recovery method according to an embodiment of this
application;
[0145] FIG. 4 is a schematic flowchart of another example of a link
failure recovery method according to an embodiment of this
application;
[0146] FIG. 5 is a schematic block diagram of an example of a link
failure recovery apparatus according to an embodiment of this
application;
[0147] FIG. 6 is a schematic block diagram of another example of a
link failure recovery apparatus according to an embodiment of this
application;
[0148] FIG. 7 is a schematic diagram of a structure of a terminal
device according to an embodiment of this application; and
[0149] FIG. 8 is a schematic diagram of a structure of a network
device according to an embodiment of this application.
DESCRIPTION OF EMBODIMENTS
[0150] The following describes the technical solutions in this
application with reference to the accompanying drawings.
[0151] The technical solutions in the embodiments of this
application may be applied to various communications systems, for
example, a long term evolution (LTE) system, an LTE frequency
division duplex (FDD) system, an LTE time division duplex (TDD)
system, and a fifth generation (5G) mobile communications system or
a new radio (NR) communications system. For example, the 5G mobile
communications system includes a non-standalone (NSA) 5G mobile
communications system and/or a standalone (SA) 5G mobile
communications system. The technical solutions in the embodiments
of this application may be further applied to a future mobile
communications system and the like, for example, a sixth generation
mobile communications system.
[0152] A terminal device in the embodiments of this application may
be user equipment (UE), an access terminal device, a subscriber
unit, a subscriber station, a mobile station, a remote station, a
remote terminal device, a mobile device, a user terminal device, a
terminal device, a wireless communications device, a user agent, or
a user apparatus. The terminal device may alternatively be a
cellular phone, a cordless phone, a session initiation protocol
(SIP) phone, a wireless local loop (WLL) station, a personal
digital assistant (PDA), a handheld device having a wireless
communication function, a computing device, another processing
device connected to a wireless modem, a vehicle-mounted device, a
wearable device, a terminal device in a future 5G network, a
terminal device in a future evolved public land mobile network
(PLMN), or the like. This is not limited in the embodiments of this
application.
[0153] A network device in the embodiments of this application may
be a device configured to communicate with the terminal device. The
network device may be a base transceiver station (BTS) in global
system for mobile communications (GSM) or code division multiple
access (CDMA), or may be a NodeB (NB) in a wideband code division
multiple access (WCDMA) system, or may be an evolved NodeB (eNB or
eNodeB) in an LTE system, or may be a radio controller in a cloud
radio access network (CRAN) scenario. Alternatively, the network
device may be a relay node, an access point, a vehicle-mounted
device, a wearable device, a network device in a future 5G network,
a network device in a future evolved PLMN network, or the like.
This is not limited in the embodiments of this application.
[0154] In the embodiments of this application, the terminal device
or the network device includes a hardware layer, an operating
system layer running above the hardware layer, and an application
layer running above the operating system layer. The hardware layer
includes hardware such as a central processing unit (CPU), a memory
management unit (MMU), and a memory (which is also referred to as a
main memory). The operating system may be any one or more computer
operating systems that implement service processing through a
process, for example, a Linux operating system, a Unix operating
system, an Android operating system, an iOS operating system, or a
Windows operating system. The application layer includes
applications such as a browser, an address book, word processing
software, and instant messaging software. In addition, a specific
structure of an execution body of a method provided in the
embodiments of this application is not specifically limited in the
embodiments of this application, provided that a program that
records code of the method provided in the embodiments of this
application can be run to perform communication according to the
method provided in the embodiments of this application. For
example, the method provided in the embodiments of this application
may be performed by the terminal device or the network device, or a
functional module that can invoke and execute the program in the
terminal device or the network device.
[0155] In addition, aspects or features of this application may be
implemented as a method, an apparatus, or a product that uses
standard programming and/or engineering technologies. The term
"product" may cover a computer program that is accessed from any
computer-readable component, carrier, or medium. For example, a
computer-readable medium may include but is not limited to a
magnetic storage component (for example, a hard disk, a floppy
disk, or a magnetic tape), an optical disc (for example, a compact
disc (CD) or a digital versatile disc (DVD)), a smart card, and a
flash memory component (for example, an erasable programmable
read-only memory (EPROM), a card, a stick, or a key drive). In
addition, various storage media described in this specification may
represent one or more devices and/or other machine-readable media
that are configured to store information. The term
"machine-readable media" may include but is not limited to a radio
channel and various other media that can store, include, and/or
carry instructions and/or data.
[0156] FIG. 1 is a schematic architectural diagram of a mobile
communications system to which an embodiment of this application is
applicable. The communications system in FIG. 1 may include at
least one terminal device (for example, a terminal device 10, a
terminal device 20, a terminal device 30, a terminal device 40, a
terminal device 50, and a terminal device 60) and a network device
70. The network device 70 is configured to provide a communication
service for the terminal device and enable the terminal device to
access a core network. The terminal device may access a network by
searching for a synchronization signal, a broadcast signal, or the
like sent by the network device 70, to communicate with the
network. The terminal device 10, the terminal device 20, the
terminal device 30, the terminal device 40, and the terminal device
60 in FIG. 1 may perform uplink and downlink transmission with the
network device 70. For example, the network device 70 may send
downlink signals to the terminal device 10, the terminal device 20,
the terminal device 30, the terminal device 40, and the terminal
device 60, or may receive uplink signals sent by the terminal
device 10, the terminal device 20, the terminal device 30, the
terminal device 40, and the terminal device 60.
[0157] In addition, the terminal device 40, the terminal device 50,
and the terminal device 60 may also be considered as a
communications system. The terminal device 60 may send downlink
signals to the terminal device 40 and the terminal device 50, or
may receive uplink signals sent by the terminal device 40 and the
terminal device 50.
[0158] It should be noted that the embodiments of this application
may be applied to a communications system including one or more
network devices, or may be applied to a communications system
including one or more terminal devices. This is not limited in this
application.
[0159] To facilitate understanding of this application, the
following describes terms related to this application.
[0160] 1. Control Resource Set (CORESET)
[0161] To improve efficiency of blindly detecting a control channel
by a terminal device, the concept of control resource set is
proposed in an NR standard formulation process. A network device
may configure one or more resource sets for the terminal device, to
send a physical downlink control channel (PDCCH). The network
device may send a control channel to the terminal device on any
control resource set corresponding to the terminal device. In
addition, the network device further needs to notify the terminal
device of another configuration, for example, a search space set,
associated with the control resource set. Configuration information
of all control resource sets varies. For example, frequency-domain
widths vary, or time-domain lengths vary. It is extensible that the
control resource set in this application may be a CORESET, a
control region, or an enhanced physical downlink control channel
(ePDCCH) set that is defined in a 5G mobile communications
system.
[0162] A time-frequency position occupied by the PDCCH may be
referred to as a downlink control region. In LTE, the PDCCH is
always located on the first m (where possible values of m are 1, 2,
3, and 4) symbols of a subframe. It should be noted that an E-PDCCH
and an R-PDCCH in LTE are not located on the first m symbols.
[0163] In NR, the downlink control region may be flexibly
configured in the control resource set (CORESET) and the search
space set (search space set) by using RRC signaling.
[0164] Information such as a frequency domain position of the PDCCH
or a control channel element (CCE) and a quantity (where a maximum
value is 3) of continuous time-domain symbols may be configured in
the control resource set.
[0165] Information such as a PDCCH detection periodicity, an
offset, and a start symbol in a slot may be configured in the
search space set.
[0166] For example, if it may be configured in the search space set
that a PDCCH periodicity is one slot and a start symbol in time
domain is a symbol 0, the terminal device may detect the PDCCH at a
start position of each slot.
[0167] 2. Quasi-Colocation (QCL) Assumption Information
[0168] Quasi co-site/quasi-colocation QCL assumption information
may also be referred to as QCL information. The QCL information is
used to assist in describing receiving beamforming information by
the terminal device and a receiving procedure.
[0169] The QCL information is used to indicate a QCL relationship
between two types of reference signals. A target reference signal
may be usually a demodulation reference signal (DMRS), a channel
state information reference signal (CSI-RS), or the like. A
referenced reference signal or a source reference signal may be
usually a CSI-RS, a tracking reference signal (TRS), a
synchronization signal/physical broadcast channel block
(synchronous signal/PBCH block, SSB), a sounding reference signal
(SRS), or the like.
[0170] It should be understood that spatial characteristic
parameters of two reference signals or channels that satisfy a QCL
relationship are the same, so that a spatial characteristic
parameter of the target reference signal can be inferred based on a
resource index of the source reference signal.
[0171] It should be further understood that spatial characteristic
parameters of two reference signals or channels that satisfy
spatial relation information are the same, so that the spatial
characteristic parameter of the target reference signal can be
inferred based on the resource index of the source reference
signal.
[0172] The spatial characteristic parameter includes one or more of
the following parameters:
[0173] an angle of arrival (AoA), a dominant angle of arrival AoA,
an average angle of arrival, a power angular spectrum (PAS) of the
angle of arrival, an angle of departure (AoD), a dominant angle of
departure, an average angle of departure, a power angular spectrum
of the angle of departure, transmit beamforming of the terminal
device, receive beamforming of the terminal device, spatial channel
correlation, transmit beamforming of the network device, receive
beamforming of the network device, an average channel gain, an
average channel delay (average delay), a delay spread, a Doppler
spread, a Doppler shift, a spatial reception parameter (spatial Rx
parameters), or the like.
[0174] These spatial characteristic parameters describe a
characteristic of a spatial channel between an antenna port for the
source reference signal and an antenna port for the target
reference signal, and help the terminal device complete
receive-side beamforming or a receiving processing process based on
the QCL information. It should be understood that, the terminal
device may receive the target reference signal based on information
about a receive beam for the source reference signal indicated by
the QCL information. These spatial characteristic parameters
further help the terminal device complete transmit-side beamforming
or a transmission processing process based on the spatial relation
information. It should be understood that the terminal device may
transmit the target reference signal based on information about a
transmit beam for the source reference signal indicated by the
spatial correlation information.
[0175] To reduce overheads of indicating the QCL information by the
network device for the terminal device, in an optional
implementation, the network device may indicate that a demodulation
reference signal of the PDCCH or a physical downlink shared channel
(PDSCH) and one or more of a plurality of reference signal
resources previously reported by the terminal device satisfy a QCL
relationship. For example, the reference signal may be a CSI-RS.
Herein, an index of each reported CSI-RS resource corresponds to
one transmit-receive beam pair previously established during
measurement performed based on the CSI-RS resource. It should be
understood that information about receive beams for the two
reference signals or channels that satisfy the QCL relationship is
the same, and the terminal device may infer, based on the indexes
of the reference signal resources, information about receive beams
for receiving the PDCCH or the PDSCH.
[0176] Four types of QCL are defined in an existing standard, and
the network device may simultaneously configure one or more types
of QCL for the terminal device, for example, QCL types A+D, and QCL
types C+D:
[0177] QCL types A: Doppler shift, Doppler spread, average delay,
delay spread
[0178] QCL types B: Doppler shift, Doppler spread
[0179] QCL types C: average delay, Doppler shift
[0180] QCL types D: Spatial Rx parameter
[0181] In an example of this application, correspondences of some
parameters may also be used in descriptions of a QCL scenario.
[0182] It should be understood that in a scenario applicable to QCL
assumption in this application, there may alternatively be an
association relationship between two reference signals, or may
further be an association relationship between transmission
objects.
[0183] It should be understood that, in this application, there is
a similar concept for uplink signal sending, for example, spatial
relation information. The spatial relation information is used to
assist in describing transmit-side beamforming information and a
transmission procedure of the terminal device.
[0184] The spatial relation information is used to indicate a
spatial transmit parameter relationship between two types of
reference signals. The target reference signal may be usually a
DMRS, an SRS, or the like, and the referenced reference signal or
the source reference signal may be usually a CSI-RS, an SRS, an
SSB, or the like.
[0185] 3. Transmission Configuration Indicator (TCI) State
[0186] A TCI is used to indicate QCL information of a PDCCH/CORESET
or a PDSCH. TCI information indicates that a reference signal
included in a TCI and a DMRS of the PDCCH/PDSCH satisfy a QCL
relationship, and is mainly used to indicate that during reception
of the PDCCH/PDSCH, information such as a spatial reception
parameter of the PDCCH/PDSCH is the same as, similar to, or
approximate to information such as a spatial reception parameter of
the reference signal included in the TCI.
[0187] One TCI state may include one or two referenced reference
signals and an associated QCL type. The QCL type may further be
classified into four categories: A, B, C, and D that are different
combinations or selections of {Doppler shift, Doppler spread,
average delay, delay spread, spatial Rx parameter}. The TCI state
includes QCL information, or the TCI state is used to indicate QCL
information.
[0188] 4. Synchronization Signal/Physical Broadcast Channel Block
(Synchronous Signal/PBCH Block, SS/PBCH Block)
[0189] An SS/PBCH block may also be referred to as an SSB. PBCH is
an abbreviation of a physical broadcast channel. The SSB includes
at least one of a primary synchronization signal (PSS), a secondary
synchronization signal (SSS), and a PBCH. The SSB is a signal
mainly used for cell searching, cell synchronization, and carrying
broadcast information.
[0190] 5. Concepts Related to Cells and Carriers:
[0191] Carrier Aggregation (CA):
[0192] A plurality of consecutive or non-consecutive component
carriers are aggregated into a larger bandwidth (for example, up to
100 MHz), thereby satisfying a bandwidth requirement of the
3GPP.
[0193] Component Carrier (CC):
[0194] Each carrier in multi-carrier aggregation may be referred to
as a "CC". Each carrier includes one or more physical resource
blocks (PRBs). There may be a corresponding physical downlink
control channel (PDCCH) on each carrier, and the PDCCH is used to
schedule a physical downlink control channel (PDSCH) on the
respective CC. Alternatively, there may be no PDCCH, but the PDSCH
is scheduled by using a PDCCH on another CC. When the terminal
device may receive data on a plurality of CCs, the CCs may also be
referred to as component carriers, component carriers, component
carriers, or the like.
[0195] Primary Cell (PCell):
[0196] A PCell is a cell on which a CA terminal device camps. The
CA terminal device corresponds to a physical uplink control channel
(physical uplink control channel, PUCCH). Generally, only the PCell
has a PUCCH.
[0197] Primary Secondary Cell (PSCell):
[0198] A PSCell is a special secondary cell that is of a secondary
eNodeB (SeNB) and that is configured by a master eNodeB (MeNB) for
DC UE by using RRC connection signaling.
[0199] Secondary Cell (SCell):
[0200] An SCell is a cell configured for the CA terminal device by
using RRC connection signaling, works on an SCC (secondary
component carrier), and may provide more radio resources for the CA
terminal device. In the SCell, there can be downlink transmission
only or both downlink and uplink transmission.
[0201] Special Cell (Special Cell, SPCell):
[0202] In a dual connectivity (DC) scenario, an SPCell is a PCell
in a master cell group (MCG) or a PSCell in a secondary cell group
(SCG). Otherwise, in a CA scenario, the SPCell is a PCell.
[0203] MCG/SCG:
[0204] MCG: A group to which cells that provide services for the
terminal device and that are served by a master eNodeB belong is a
master cell group. In a dual connectivity mode, a group of serving
cells associated with the MeNB includes a PCell and one or more
SCells.
[0205] SCG: A group to which cells that provide services for the UE
and that are served by a secondary eNodeB belong is a secondary
cell group. In the dual connectivity mode, a PSCell and zero or
more SCells are included.
[0206] MeNB/SeNB:
[0207] An MeNB is a base station that serves a cell on which the DC
terminal device camps.
[0208] An SeNB is another base station configured by the MeNB for
the DC UE by using RRC connection signaling.
[0209] 6. Beam:
[0210] A beam is a communication resource. The beam may be a wide
beam, a narrow beam, or another type of beam. A beamforming
technology may be a beamforming technology or another technical
means. The beamforming technology may be specifically a digital
beamforming technology, an analog beamforming technology, or a
hybrid digital/analog beamforming technology. Different beams may
be considered as different resources. Same information or different
information may be sent on different beams. In one embodiment, a
plurality of beams having a same communication feature or similar
communication features may be considered as one beam. One beam may
include one or more antenna ports, configured to transmit a data
channel, a control channel, a sounding signal, and the like. For
example, a transmit beam may be distribution of signal strength
formed in different directions in space after a signal is
transmitted by using an antenna, and a receive beam may be
distribution of signal strength, in different directions in space,
of a radio signal received from an antenna. It may be understood
that the one or more antenna ports forming the beam may
alternatively be considered as one antenna port set.
[0211] Beams may be classified into a transmit beam and a receive
beam of the network device, and a transmit beam and a receive beam
of the terminal device. The transmit beam of the network device is
used to describe transmit-side beamforming information of the
network device, and the receive beam of the base station is used to
describe receive-side beamforming information of the network
device. The transmit beam of the terminal device is used to
describe transmit-side beamforming information of the terminal
device, and the receive beam of the terminal is used to describe
receive-side beamforming information of the terminal device. In
other words, the beam is used to describe beamforming
information.
[0212] The beam may correspond to a time resource, and/or a space
resource, and/or a frequency domain resource.
[0213] In one embodiment, the beam may further correspond to a
reference signal resource (for example, a reference signal resource
for beamforming) or beamforming information.
[0214] In one embodiment, the beam may further correspond to
information associated with a reference signal resource of the
network device. A reference signal may be a channel state
information reference signal (CSI-RS), an SSB, a demodulation
reference signal (DMRS), a phase tracking signal (PTRS), a tracking
signal (TRS), or the like. The information associated with the
reference signal resource may be a reference signal resource
identifier, QCL information (especially the QCL type D), or the
like. The reference signal resource identifier corresponds to a
transmit-receive beam pair that is previously established during
measurement based on the reference signal resource. The terminal
may infer beam information based on the reference signal resource
index.
[0215] In one embodiment, the beam may further correspond to a
spatial domain filter (spatial filter or spatial domain filter), or
a spatial domain transmission filter.
[0216] Different types of reference signals are generally used in a
communications system, where one type of reference signal is used
to estimate a channel, to perform coherent demodulation on a
received signal including control information or data, and another
type of reference signal is used for measurement of a channel state
or channel quality, to implement scheduling on the terminal device.
The terminal device obtains channel state information (CSI) through
measurement based on channel quality of a CSI-RS. The CSI includes
at least one of a rank indicator (RI), a precoding matrix indicator
(precoding matrix indicator, PMI), a channel quality indicator
(CQI), or the like. The CSI information may be sent by the terminal
device to a base station through a physical uplink control channel
or a physical uplink shared channel.
[0217] With emergence of intelligent terminals, especially
emergence of video services, current spectrum resources can hardly
match an explosive growth of user requirements on a capacity. A
high frequency band with a larger available bandwidth, especially a
millimeter-wave band, gradually becomes a candidate frequency band
of a next generation communications system. In addition, in a
modern communications system, a multi-antenna technology is usually
used to increase a capacity and coverage of the system, or improve
user experience. Another advantage of using the high frequency band
is that a size of a multi-antenna configuration can be greatly
reduced, to facilitate site obtaining and deployment of more
antennas. However, a difference from an operating frequency band in
an existing system such as an LTE system lies in that, the high
frequency band causes a larger path loss, and especially, a loss in
radio propagation further becomes larger due to factors such as
atmosphere and vegetation.
[0218] To overcome the larger propagation loss, a signal
transmission mechanism that is based on a beamforming technology is
applied, with the intention of using a relatively high antenna gain
to compensate for the loss in a signal propagation process.
Beamforming signals may include a broadcast signal, a
synchronization signal, a cell-specific reference signal, and the
like.
[0219] When a signal is transmitted based on the beamforming
technology, once a user moves, a direction of a beamformed beam
corresponding to the transmitted signal may not match a position of
the user after the movement, and interruption to receiving of the
signal may occur frequently. To track changes of the beamformed
beam in the signal transmission process, channel quality
measurement and result reporting based on the beamforming
technology are introduced. The channel quality measurement may be
based on a beamformed synchronization signal or cell-specific
reference signal. The user performs handover between different
beamformed beams more dynamically and frequently than handover
between cells. Therefore, a dynamic measurement and reporting
mechanism is required. In one embodiment, similar to CSI
information reporting, reporting of a channel quality result of the
beamformed beam may also be sent by the terminal device to the base
station through a physical uplink control channel or a physical
uplink shared channel.
[0220] After measuring a plurality of beams sent by the base
station, the terminal device selects N better beams of the base
station, and reports measurement information of the N better beams
to the base station. The beam measurement information is beam state
information (BSI), and content thereof mainly includes a beam index
and reference signal received power (RSRP) of a beam. In a beam
training process, the network device measures a plurality of beams
sent by the terminal device, and notifies the terminal device of a
better beam in the plurality of beams sent by the terminal device,
for example, notifies the terminal device by using a reference
signal resource, for example, a beam index 1. The receive beam of
the terminal device is indicated by using a spatial RX parameter in
the QCL, and the beam state information may be described as L1-RSRP
related information.
[0221] Specifically, the beam training process includes the
following operations.
[0222] (1) Select N best beam pairs (BPLs) (one BPL includes one
transmit beam of the base station and one receive beam of the
terminal device, or one BPL includes one transmit beam of the
terminal device and one receive beam of the base station). The
terminal device selects the transmit beam of the base station
and/or the receive beam of the terminal based on beam sweeping
performed by the network device, and the network device selects a
transmit beam of the terminal and/or a receive beam of the base
station based on beam sweeping performed by the terminal
device.
[0223] (2) Update a transmit beam. The transmit beam may be a
transmit beam of the base station, or may be a transmit beam of the
terminal device. When the transmit beam is the transmit beam of the
base station, the base station sends reference signals to the
terminal device by using different transmit beams, and the terminal
device receives, by using a same receive beam, the reference
signals that are sent by the base station by using the different
transmit beams, determines a best transmit beam of the base station
based on the received signals, and then feeds back the best
transmit beam of the base station to the base station, so that the
base station updates the transmit beam. When the transmit beam is
the transmit beam of the terminal, the terminal device sends
reference signals to the base station by using different transmit
beams, and the base station receives, by using a same receive beam,
the reference signals that are sent by the terminal device by using
the different transmit beams, determines a best transmit beam of
the terminal device based on the received signals, and then feeds
back the best transmit beam of the terminal device to the terminal
device, so that the terminal device updates the transmit beam. The
process of sending the reference signals by using different
transmit beams may be referred to as beam sweeping, and the process
of determining the best transmit beam based on the received signals
may be referred to as beam matching.
[0224] (3) Update a receive beam. The receive beam may be a receive
beam of the base station, or may be a receive beam of the terminal
device. When the receive beam is the receive beam of the base
station, the terminal device sends reference signals to the base
station by using a same transmit beam, and the base station
receives, by using different receive beams, the reference signals
sent by the terminal device, and then determines a best receive
beam of the base station based on the received signals, to update
the receive beam of the base station. When the receive beam is the
receive beam of the terminal device, the base station sends
reference signals to the terminal device by using a same transmit
beam, and the terminal device receives, by using different receive
beams, the reference signals sent by the base station, and then
determines a best receive beam of the terminal device based on the
received signals, to update the receive beam of the terminal
device.
[0225] During downlink signal transmission, both the transmit beam
of the base station and the receive beam of the terminal device may
dynamically change, and there may be a plurality of best receive
beams determined by the terminal device based on the received
signals. To enable the terminal device to determine a receive beam
of the terminal device, the terminal device may feed back
information about the plurality of receive beams to the network
device, and the network device may indicate the receive beam of the
terminal to the terminal device by sending beam indication
information to the terminal device. When the terminal device uses
analog beamforming, the terminal device may precisely determine the
receive beam of the terminal based on the beam indication
information sent by the network device. Therefore, beam sweeping
time of the terminal device can be shortened, and power is
saved.
[0226] In the beam training process described above, the base
station obtains N better beam pairs BPLs for communication with the
terminal device, where the beam pairs BPLs are <Bx, B'x> and
<By, B'y>, where Bx represents a transmit beam of the base
station, B'x represents a receive beam of the terminal device, By
represents a transmit beam of the terminal device, and B'y
represents a receive beam of the base station. In a subsequent
process of communication with the terminal device, the base station
uses the N BPLs for data transmission. However, because of blocking
in a communication process and a poor diffraction capability in a
high frequency channel, a current serving beam is blocked, and a
signal cannot be further transmitted. To prevent sudden
communication interruption caused by beam blocking, a corresponding
mechanism needs to be introduced to detect beam quality and quickly
recover a link when the beam is blocked.
[0227] 7. Reference Signal Configured for Link Failure Detection
and Link Failure Recovery
[0228] To detect and recover a link fault, the network device may
configure, for the terminal device, a reference signal resource set
(for example, a beam failure detection RS resourceconfig, a beam
failure detection RS, or failure detection resources) (which may
also be referred to as a link failure detection reference signal
resource set) used for beam failure detection. The network device
may further configure, for the terminal device, a reference signal
resource set (a candidate beam RS list, a candidate beam RS
identification resource, a beam failure candidate beam resource, a
candidate beam identification RS, or a candidate beam list) (which
may also be referred to as a candidate reference signal resource
set or a link failure recovery reference signal resource set) used
to recover a link between the terminal device and the network
device. In addition, a reference signal used to detect the link
failure may alternatively be implicitly indicated, and a reference
signal associated with a TCI indicating a PDCCH is used as the
reference signal for detecting the link failure. The reference
signal is a reference signal that satisfies a QCL relationship with
a DMRS on the PDCCH and that is periodically sent. An RS in a beam
failure detection RS set and the demodulation reference signal on
the physical downlink control channel PDCCH satisfy the QCL
relationship or use a same TCI state as the PDCCH. When channel
quality information (for example, reference signal received power
(RSRP), a channel quality indicator (CQI), a block error rate
(BLER), a signal to interference plus noise ratio (SINR), and a
signal-to-noise ratio (SNR)) of some or all reference signals in
the set is less than a predetermined threshold, it is determined
that a communications link is faulty. Being less than the
predetermined threshold may be being less than the predetermined
threshold for W consecutive times or being less than the
predetermined threshold for W times in a time period. In one
embodiment, the predetermined threshold may be the same as a radio
link failure out-of-synchronization (radio link failure OOS (out of
sync)) threshold. The predetermined threshold may be referred to as
a link failure detection threshold, or may be referred to as a link
failure threshold. It should be understood that, any threshold used
for link failure detection may be the predetermined threshold, and
a name of the predetermined threshold is not limited in the present
disclosure.
[0229] After a beam failure, the terminal device needs to select,
from the candidate reference signal resource set, a reference
signal resource whose channel quality information (such as RSRP or
a CQI) is greater than the predetermined threshold, to recover the
communications link. In one embodiment, the predetermined threshold
may be configured by the network device. Herein, a beam failure
detection RS is used by the terminal to detect channel quality of a
transmit beam of the network device, and the transmit beam is a
beam used when the network device communicates with the terminal. A
candidate beam identification RS is a reference signal set used by
the terminal device to initiate link reconfiguration after the
terminal device determines that a communications link fault occurs
on the transmit beam of the network device.
[0230] It should be understood that, in the embodiments of this
application, a communication failure may also be referred to as a
communications link failure, a communications link fault, a link
fault, a link failure, a communication fault, a beam failure, a
beam fault, or the like. In the embodiments of this application,
these concepts have a same meaning. The communication failure may
mean that signal quality of a reference signal used for PDCCH beam
failure detection is less than or equal to a preset threshold.
After the communications link is faulty, the terminal device needs
to select, from a candidate reference signal resource set, a
reference signal resource whose channel quality information (such
as RSRP, RSRQ, a CQI, or an SINR) is greater than the predetermined
threshold, to recover the communications link.
[0231] In one embodiment, the predetermined threshold may be
configured by the network device, or may be a predefined threshold.
For example, when the network device does not configure the
threshold, a threshold used for mobility measurement is used by
default. The predetermined threshold may be referred to as a link
failure recovery threshold, or may be referred to as a link
recovery threshold. It should be understood that, any threshold
used for link failure recovery may be the predetermined threshold,
and a name of the predetermined threshold is not limited in the
present disclosure. The candidate beam identification RS is a
reference signal set used by the terminal device to initiate link
reconfiguration after the terminal device determines that the
communications link fault occurs on the transmit beam of the
network device.
[0232] In the embodiments of this application, communication
failure recovery may also be referred to as recovery of
communication between the network device and the terminal device,
communication fault recovery, link failure recovery, link fault
recovery, beam failure recovery, beam fault recovery,
communications link failure recovery, communications link fault
recovery, link reconfiguration, or the like.
[0233] During specific implementation, the two sets, namely, the
reference signal resource set used for beam failure detection and
the reference signal resource set used to recover the link between
the terminal device and the network device may alternatively have
other names. This is not specifically limited in this
application.
[0234] In the embodiments of this application, communication
failure recovery request information may also be referred to as
communication fault recovery request information, link failure
recovery request information, link fault recovery request
information, beam failure recovery request information, beam fault
recovery request information, communications link failure recovery
request information, communications link fault recovery request
information, link reconfiguration request information,
reconfiguration request information, or the like. It should be
understood that, in the embodiments of this application, the
communication failure recovery request information may be referred
to as a first request message, a second request message, and/or a
third request message.
[0235] In the embodiments of this application, communication
failure recovery response information may also be referred to as
communication failure response information, beam failure recovery
response information, beam failure response information,
communications link fault recovery response information,
communications link fault response information, communications link
failure recovery response information, communications link failure
response information, beam fault recovery response information,
beam fault response information, link reconfiguration response
information, link fault recovery response information, link fault
response information, link failure recovery response information,
link failure response information, communication fault recovery
response information, communication fault response information,
reconfiguration response information, or the like. It should be
understood that, in this application, the communication failure
recovery response information may be referred to as response
information for short.
[0236] In the embodiments of this application, In one embodiment, a
communication failure recovery request may mean sending a signal on
a resource used to carry the communication failure recovery
request. The communication failure recovery response information
may mean receiving, on a control resource set and/or a search space
set that are/is used to send a communication failure recovery
response, downlink control information (DCI) whose cyclic
redundancy check (CRC) is scrambled by using a cell radio network
temporary identifier (C-RNTI). The communication failure recovery
response information may alternatively be DCI scrambled by using
other information (for example, DCI scrambled by using a BFR-RNTI).
The communication failure recovery response information may
alternatively be data scheduled by using the DCI. The communication
failure recovery response information may alternatively be an ACK
of the data scheduled by using the DCI. The communication failure
recovery response information may alternatively be one of the
following information: DCI scrambled by using the cell radio
network temporary identifier C-RNTI, DCI scrambled by using a
modulation and coding scheme cell radio network temporary
identifier MCS-C-RNTI, downlink control information DCI in a
dedicated search space, DCI scrambled by using a dedicated radio
network temporary identifier RNTI, DCI scrambled by using a random
access radio network temporary identifier RA-RNTI, DCI including a
preset state value, DCI including transmission configuration
indicator TCI information, quasi-colocation QCL indication
information of a cell in which a link failure occurs, or DCI in a
preset format, where the DCI in the preset format indicates newly
transmitted data. This is not limited in the embodiments of this
application.
[0237] It should be understood that, in the embodiments of this
application, the communication failure, the communication failure
recovery, the communication failure recovery request information,
and the communication failure recovery response information may
alternatively have other names. This is not specifically limited in
this application.
[0238] It should be understood that, in this application, a link
recovery failure of a cell may be understood as that the terminal
device no longer sends first request information, second request
information, and/or third request information that
correspond/corresponds to the cell; may be understood as stopping
timing of a link failure recovery clock; or may be understood as
stopping counting of a link failure recovery counter, or the like.
Alternatively, a link recovery failure of a cell may be understood
as that no response information of the cell is received yet when a
link failure recovery clock corresponding to the cell expires
and/or counting of a link failure recovery counter exceeds a
maximum quantity of times or reaches the maximum quantity of times.
The link failure recovery counter is used to count a quantity of
times that the link failure recovery request information is sent.
In one embodiment, a media access control (MAC) layer of the
terminal device maintains a link failure recovery timer (beam
failure recovery timer) and a link failure recovery counter (beam
failure recovery counter). The link failure recovery timer is used
to control an entire time length of link failure recovery. The link
failure recovery counter is used to limit a quantity of times that
the terminal device sends a link failure recovery request. When the
link failure recovery counter reaches a maximum value, the terminal
device considers that the link failure recovery fails, and stops a
link failure recovery process. A time length of recovery of the
recovery timer and a count value of the recovery counter may be
configured by the network device, or may be preset values.
[0239] It should be understood that, in this application, a link
recovery success of a cell may be understood as that the terminal
device detects response information of the cell.
[0240] It should be understood that "detection" in the embodiments
of this application may be understood as "receiving", or may be
understood as "decoding".
[0241] It should be understood that, in this application, a time
unit may be one or more radio frames, one or more subframes, one or
more slots, one or more mini-slots, one or more orthogonal
frequency division multiplexing (OFDM) symbols, or the like defined
in an LTE system or a 5G NR system, or may be a time window
including a plurality of frames or subframes, for example, a system
information (SI) window.
[0242] It should be understood that, "occurrence of a link failure"
may be replaced with "a link failure" in the embodiments of this
application.
[0243] It should be understood that, in the embodiments of this
application, "information about a first state" may be replaced with
the "first state", or "information about the first state" and the
"first state" are equivalent concepts.
[0244] It should be understood that, in the embodiments of this
application, the "preset threshold" may be replaced with the
"predetermined threshold", or the "preset threshold" and the
"predetermined threshold" are equivalent concepts.
[0245] It should be understood that, in this application, a "first
reference signal" is a corresponding reference signal in a first
reference signal resource set, and the first reference signal
resource set may be a candidate reference signal set. The first
reference signal resource set is a reference signal resource set
used to recover a link of a first cell. The corresponding reference
signal in the first reference signal resource set may be a
reference signal of the first cell, or may be a reference signal of
another cell. In other words, the corresponding reference signal
resource in the first reference signal resource set may be a
reference signal resource of the first cell, or may be a reference
signal resource of another cell. This is not limited in the
embodiments of this application.
[0246] It should be understood that, in the embodiments of this
application, interaction between the terminal device and the
network device is generally corresponding. To be specific, the
terminal device sends information, and correspondingly, the network
device also receives the information. Alternatively, the network
device sends information, and correspondingly, the terminal device
also receives the information. Further, physical resources used by
the network device and the terminal device to send and receive
information or rules, for example, periodicities or priority
sequences applied by the network device and the terminal device to
send and receive the information are also corresponding. This is
not limited in the embodiments of this application.
[0247] It should be understood that, for definitions of the
foregoing terms, refer to the conventional technology. However,
with continuous development of technologies, the foregoing
definitions may also change. This is not limited in the embodiments
of this application.
[0248] FIG. 2 is a schematic flowchart of a link failure recovery
method. As shown in FIG. 2, the link failure recovery method 200
includes the following content.
[0249] 201: A terminal device detects a working state of a current
link. For example, the terminal device may detect the current link,
and determine that the current link fails.
[0250] It should be understood that a link in this application may
be understood as a "beam". That is, the terminal fails to transmit
a signal by using a current beam.
[0251] For example, when the terminal device determines that
channel quality information of a beam failure detection RS or
channel quality information of all or some reference signals in a
beam failure detection RS set is less than or equal to a link
failure detection threshold for N consecutive times, the terminal
device may determine that a link between the terminal device and a
network device is faulty.
[0252] It should be understood that, in this embodiment of this
application, a manner in which the terminal device determines that
the link between the terminal device and the network device fails
is not limited to the foregoing example, and that the link between
the terminal device and the network device fails may alternatively
be determined in another determining manner. This is not limited in
this application.
[0253] 202: The terminal device selects a new link, that is, the
terminal device selects a new beam.
[0254] For example, the terminal device measures channel quality
information of a candidate reference signal set (candidate beam
identification RS), and determines, based on the channel quality
information of the candidate beam identification RS, a reference
signal (new identified beam) whose channel quality is greater than
or equal to a second preset threshold, that is, determines a new
beam.
[0255] 203: After selecting the new link, the terminal device sends
a link failure request message (BFRQ) to the network device, and
correspondingly, the network device receives the BFRQ sent by the
terminal device.
[0256] The BFRQ includes the new link selected by the terminal
device in operation 202. In other words, the BFRQ may indicate
information about a reference signal that is identified by the
terminal device and whose channel quality information is greater
than a link failure recovery threshold. The terminal device may
explicitly or implicitly notify the network device of information
about the new identified link (for example, the new beam) or a new
identified reference signal resource.
[0257] Correspondingly, after receiving the BFRQ sent by the
terminal device, the network device determines the new link based
on the information about the new link that is included in the
BFRQ.
[0258] It should be understood that, in a process in which the
terminal device sends the BFRQ to the network device, a media
access control (MAC) layer of the terminal device maintains a timer
(beam failure recovery timer) and a counter (beam failure recovery
counter). The timer (beam failure recovery timer) is used to
control an entire time length of link failure recovery. The counter
(beam failure recovery counter) is used to limit a quantity of
times that the terminal device sends a link failure recovery
request. When the timer expires or the counter reaches a maximum
value, the terminal device considers that the link failure recovery
fails, and stops a link failure recovery process.
[0259] 204: The network device sends a beam failure recovery
response message (beam failure recovery response, BFRR) to the
terminal device, and correspondingly, the terminal device receives
the BFRR sent by the network device.
[0260] The BFRR may be sent based on the information about the new
link or the information about the reference signal that is
indicated in 203.
[0261] The terminal device detects DCI in a CORESET sent by the
network device, where the CORESET may be a dedicated CORESET
resource configured by the network device for the terminal device,
and is used for: during a link failure, after the terminal device
sends a link failure request BFRQ, a downlink control resource of a
link failure response message BFRR sent by the network device to
the terminal device.
[0262] The terminal device receives the BFRR based on the
information about the new link that is included in the BFRQ. If the
terminal device receives the link failure recovery response
information, the terminal device determines that the link failure
recovery succeeds.
[0263] It should be understood that, in the link failure recovery
method 200, operation 201 may be performed earlier than operation
202, or operation 201 and operation 202 may be performed
simultaneously. A time sequence of performing operation 201 and
operation 202 is not limited in this application.
[0264] It should be further understood that, in the link failure
recovery method 200, operation 202 may be performed earlier than
operation 203, or operation 202 may be performed later than
operation 203, or operation 202 and operation 203 may be performed
simultaneously. A time sequence of performing operation 202 and
operation 203 is not limited in this application.
[0265] In the foregoing descriptions, when determining the link
failure, the terminal device may identify the information about the
new link or information about the new beam, and may notify the
network device of the information about the new link, to perform
link recovery. However, if the terminal device cannot determine a
new link or cannot find an available new link in operation 202, in
other words, the terminal device cannot find a reference signal or
a new beam (new identified beam) whose channel quality is greater
than or equal to the second preset threshold, the link failure
recovery fails. Consequently, link communication is interrupted,
and communication efficiency is reduced.
[0266] To improve link recovery reliability, this application
provides a link recovery method. When the terminal device cannot
determine a new link or cannot find an available new link, the
terminal device may indicate, to the network device in an explicit
or implicit manner, that no new link is identified, and then
perform link recovery in another manner, thereby increasing a link
failure recovery probability and improving the link recovery
reliability.
[0267] FIG. 3 is a schematic flowchart of an example of a link
failure recovery method according to an embodiment of this
application.
[0268] It should be understood that, in descriptions of this
embodiment of this application, a network device may provide one
PCell and at least one SCell for a terminal device. An example in
which a link between the SCell and the terminal device fails is
used, and each operation of the method 300 is described in detail
by using the terminal device and the network device as execution
bodies.
[0269] By way of example, and not limitation, the method 300 may
alternatively be performed by a chip used in the terminal device
and a chip used in the network device. This is not limited in this
application.
[0270] 301: The terminal device detects a working state of a
current link. For example, the terminal device may detect the
current link, and determine that the current link fails.
[0271] It should be understood that, for operation 301, refer to
operation 201 in the method 200. Specifically, when the terminal
device determines that channel quality information of a beam
failure detection RS or channel quality information of all or some
reference signals in a beam failure detection RS set is less than
or equal to a first preset threshold for N consecutive times, the
terminal device may determine that a link between the terminal
device and the network device is faulty.
[0272] It should be further understood that, in this embodiment of
this application, a manner in which the terminal device determines
that the link between the terminal device and the network device
fails is not limited to the foregoing example, and that the link
between the terminal device and the network device fails may
alternatively be determined in another determining manner. This is
not limited in this application.
[0273] 302: The terminal device determines that there is no new
link.
[0274] For example, in this application, the terminal device
detects the current link, and determines that a link failure occurs
in L SCells. No new link is identified for M SCells. In other
words, each of the M SCells has no new link. L.gtoreq.M.gtoreq.1,
and L and M are integers.
[0275] It should be understood that, that the terminal device
determines that there is no new link is that there is no new
available beam or no first reference signal corresponding to the
beam, which is referred to as a no new beam state in this
application, namely, a first state in this application. It may be
understood that, the first state is a state in which each of the M
first cells has no first reference signal that satisfies a first
preset condition, and the first preset condition is used to
determine that no new link is identified for the M SCells.
[0276] In another embodiment, the terminal device may determine, in
one or more of the following manners, that there is no new
link:
[0277] (1) The terminal device determines that no candidate beam
list is configured, and a link recovery threshold is
configured.
[0278] It should be understood that, the link recovery threshold
herein may be a preset threshold. Value relationships between the
preset threshold and the first preset threshold and between the
preset threshold and a second preset threshold, and a channel
quality type are not limited in this application. In one
embodiment, the link recovery threshold may be equal to the second
preset threshold or the first preset threshold.
[0279] It should be further understood that, the preset threshold
(for example, the first preset threshold, the second preset
threshold, or the link recovery threshold) in this application may
be preconfigured or predefined in a protocol. A configuration
manner of the preset threshold is not limited in this
application.
[0280] (2) The terminal device determines that a candidate beam
list is configured, and no link recovery threshold is
configured.
[0281] (3) The terminal device determines that a candidate beam
list and a link recovery threshold are configured, but the terminal
device identifies, from the candidate beam list, no reference
signal greater than the link recovery threshold.
[0282] (4) The terminal device determines that neither a candidate
beam list nor a link recovery threshold is configured. In this
case, it may be considered by default that there is no new
link.
[0283] 303: The terminal device sends a first request message to
the network device, and correspondingly, the network device
receives the first request message sent by the terminal device,
where the first request message indicates cell information of a
cell in which a link failure occurs.
[0284] In one embodiment, the first request message may be a first
link failure request message, scheduling request information, or a
combination of the two. This is not limited in this
application.
[0285] In a possible implementation, the first indication
information includes a first part of content and/or a second part
of content, the first part of content is used to indicate an
identifier of one or more cells in which a link failure occurs, and
the second part of content is used to indicate whether a new link
is identified for each cell in which the link failure occurs.
[0286] It should be understood that, in this implementation,
operation 302 is an optional operation.
[0287] For example, it is assumed that the network device provides
Q SCells for the terminal device (In one embodiment, the Q SCells
are SCells that require link failure detection, that is, the
network device configures the Q SCells that require link failure
detection). The terminal device determines that a link failure
occurs in three SCells, and the terminal device reports identifiers
(IDs) of the three SCells in which the link failure occurs to the
network device. As shown in the following Table 1, the identifiers
of the three SCells in which the link failure occurs are
respectively C1, C2, and C3. The first part of content may include
the identifiers of the three cells in which the link failure
occurs, and the second part of content may include information
indicating whether a new link is identified for each of the three
cells. For example, for C1 and C3, no new link is identified, and
for C2, a new link is identified. In one embodiment, the second
part of content may be indicated by using indication information of
several bits (bits). For example, "000" indicates that no new link
is identified for the cell whose identifier is C1, and "001"
indicates that a new link is identified for the cell whose
identifier is C1. Content of the first indication information is
not limited in this application.
TABLE-US-00001 TABLE 1 SCell identifier Whether a new link is
identified (first part of content) (second part of content) C1 No
C2 Yes C3 No
[0288] It should be understood that, in the foregoing
implementation, the first part of content may indicate an
identifier of one or more cells in which a link failure occurs, and
a maximum value of a quantity of cells in which a link failure
occurs and that are indicated by the first part of content may be
configured by the network device, or may be reported by the
terminal device, or may be reported by a terminal device
capability, or may be predefined in a protocol.
[0289] It should be understood that, in the foregoing
implementation, the first indication information may have a
plurality of forms. The following describes in detail the first
indication information in some possible cases, and describes
possible resource configuration manners of the first part of
content and the second part of content in this implementation by
cases.
[0290] Case 1
[0291] The first part of content and the second part of content are
carried on one resource. The resource may be a PRACH resource
(contention-based or non-contention-based), a PUCCH resource, a
semi-persistent PUSCH resource, or the like.
[0292] Hybrid mapping (or referred to as hybrid encoding) may be
performed on the first part of content and the second part of
content. It may be understood that a first part of content of a
first cell follows a second part of content of the first cell. For
example, the network device provides, for the terminal device, four
SCells (for example, C1, C2, C3, and C4) that require link failure
recovery detection. The terminal device determines that a link
failure occurs in three SCells (for example, C1, C2, and C3), and
the terminal device reports, to the network device, binary state
values (for example, 00, 01, and 10) corresponding to identifiers
of the three SCells in which the link failure occurs. The
identifiers of the three SCells in which the link failure occurs
are respectively C1, C2, and C3. The first part of content may
include the identifiers of the three cells in which the link
failure occurs, and the second part of content may include
information indicating whether a new link is identified for each of
the three cells. For example, for C1 and C3, no new link is
identified, and for C2, a new link is identified. For example, "0"
indicates that no new link is identified, and "1" indicates that a
new link is identified. The content of the first indication
information is not limited in this application. Details are shown
in the following Table 2.
TABLE-US-00002 TABLE 2 SCell identifier Whether a new link is
identified (first part of content) (second part of content) 00 0 01
1 10 0
[0293] The content of the first indication information may be
000011100. The first three bits indicate a first part of content
(cell identifier) and a second part of content (state information
indicating whether a new link is identified) of the 1st cell in
which a link failure occurs. The middle three bits indicate a first
part of content and a second part of content of the 2.sup.nd cell
in which a link failure occurs. Similarly, a same method is used
for the following three bits.
[0294] The first part of content and the second part of content may
be mapped separately. It may be understood that, first parts of
content of all first cells in which a link failure occurs follow
second parts of content of all the first cells in which the link
failure occurs. For example, the network device provides, for the
terminal device, four SCells (for example, C1, C2, C3, and C4) that
require link failure recovery detection. The terminal device
determines that a link failure occurs in three SCells (for example,
C1, C2, and C3), and the terminal device reports, to the network
device, binary state values (for example, 00, 01, and 10)
corresponding to identifiers of the three SCells in which the link
failure occurs. The identifiers of the three SCells in which the
link failure occurs are respectively C1, C2, and C3. The first part
of content may include the identifiers of the three cells in which
the link failure occurs, and the second part of content may include
information indicating whether a new link is identified for each of
the three cells. For example, for C1 and C3, no new link is
identified, and for C2, a new link is identified. For example, "0"
indicates that no new link is identified, and "1" indicates that a
new link is identified. The content of the first indication
information is not limited in this application. As shown in Table
2, the content of the first indication information may be
000110010. The first six bits indicate a first part of content of
the Pt cell in which a link failure occurs, a first part of content
of the 2.sup.nd cell in which a link failure occurs, and a first
part of content of the 3.sup.rd cell in which a link failure
occurs. The last three bits indicate a second part of content,
where in the three bits, the first bit corresponds to a second part
of content of the 1.sup.st cell in which the link failure occurs,
the second bit corresponds to a second part of content of the
2.sup.nd cell in which the link failure occurs, and the third bit
corresponds to a second part of content of the 3.sup.rd cell in
which the link failure occurs.
[0295] The first part of content and the second part of content are
carried on one resource, so that the network device can more
quickly obtain the information about the cell in which the link
failure occurs.
[0296] It should be understood that, in the case 1, the first part
of content and the second part of content may be jointly
encoded.
[0297] Case 2
[0298] The first part of content and the second part of content are
carried on different resources, and/or the first part of content
and the second part of content are independently encoded. The
resource may be a PRACH resource (contention-based or
non-contention-based), a PUCCH resource, a semi-persistent PUSCH
resource, or the like.
Example 1
[0299] The network device configures P1 first resources used to
carry the first part of content, and P2 second resources used to
carry the second part of content, where P1.gtoreq.1,
1.ltoreq.P2.ltoreq.P1, and P1 and P2 are integers. The terminal
device may implicitly report, based on an association relationship
between resources or between a resource and a cell, an identifier
of a cell in which a link failure occurs and/or a status of whether
anew link is identified for the cell in which the link failure
occurs. For example, the P1 first resources may be associated with
Q first cells. Further, P1=Q, and one of the P1 first resources may
be associated with one of the Q first cells. The P2 second
resources may be associated with the Q first cells. Further, P2=Q,
and one of the P2 second resources may be associated with one of
the Q first cells. The P2 second resources may be further
associated with the P1 first resources.
[0300] It should be understood that, indication information of a
first part of content sent by the terminal device on the one or
more first resources is used to indicate that a link failure occurs
in one or more cells corresponding to the one or more first
resources. After determining whether a new link is identified for
the one or more cells, the terminal device sends, on the second
resource corresponding to the one or more cells, indication
information of a second part of content that indicates whether a
new link is identified.
[0301] The terminal device determines that a link failure occurs in
L first cells in the Q first cells, and the terminal device
selects, at least one resource from the P1 first resources to send
a first part of content, where the first part of content indicates
cell identifiers or cell group identifiers of the L first cells in
which the link failure occurs. For example, if there is a
one-to-one correspondence between the P1 first resources and the Q
first cells, the terminal device selects L first resources that are
in the P1 first resources and that have a correspondence or
association relationship with the L first cells in which the link
failure occurs, to send the first part of content (used to indicate
that the link failure occurs in the L first cells corresponding to
the P1 first resources). The terminal device may select at least
one resource from the P2 second resources to send a second part of
content, where the second part of content indicates information
indicating whether a new link is identified for each of the L first
cells in which the link failure occurs. For example, if there is a
one-to-one correspondence between the P2 second resources and the Q
first cells, the terminal device selects L second resources that
are in the P2 second resources and that have a correspondence or
association relationship with the L first cells in which the link
failure occurs, to send the second part of content. For another
example, if there is a one-to-one correspondence between the P2
second resources and L first resources (the association
relationship is dynamic, because the L first resources are
dynamically selected, for example, it is stipulated in a protocol
that the P2 resources may be sequentially associated with the L
first resources for reporting the first part of content by the
terminal device), the terminal device selects L second resources
that are in the P2 second resources and that have a correspondence
or association relationship with the L first cells in which the
link failure occurs, to send the second part of content. For
example, the network device configures five first resources
corresponding to cells #1, #2, #3, #4, and #5, and two second
resources. The terminal determines that a link failure occurs in
the cells #1 and #5, reports a first part of content on the first
resource #1 and the first resource #5, reports a new link
identification status of the cell #1 on the second resource #1, and
reports a new link identification status of the cell #5 on the
second resource #2.
Example 2
[0302] The network device configures one first resource used to
carry the first part of content, and one second resource used to
carry the second part of content. The terminal device may report,
in an explicit manner, an identifier of a first cell in which a
link failure occurs and/or a new link identification status of the
cell in which the link failure occurs. The terminal device sends
the first part of content on the first resource, and sends the
second part of content on the second resource.
Example 3
[0303] The network device configures one first resource used to
carry the first part of content, and a plurality of second
resources used to carry the second part of content. The terminal
device may report, in an explicit manner, an identifier of a first
cell in which a link failure occurs, and/or report, in an implicit
manner, a new link identification status of the cell in which the
link failure occurs. The terminal device sends the first part of
content on the first resource, and selects at least one resource
from the plurality of second resources to send the second part of
content. A method for reporting the cell identifier in the implicit
manner is the same as that in the example 1, and details are not
described herein again.
Example 4
[0304] The network device configures a plurality of first resources
used to carry the first part of content, and one second resource
used to carry the second part of content. The terminal device may
report, in an implicit manner, an identifier of a first cell in
which a link failure occurs, and/or report, in an explicit manner,
a new link identification status of the cell in which the link
failure occurs. The terminal device selects at least one resource
from the plurality of first resources to send the first part of
content, and sends the second part of content on the second
resource. A method for reporting the second part of content in the
implicit manner is the same as that in the example 1, and details
are not described herein again.
[0305] The first part of content and the second part of content are
carried on different resources, so that the network device can
independently decode the two parts of content, and resource
configuration or encoding of the two parts of content is more
flexible. In this way, a higher decoding success rate can be
obtained. In addition, if the quantity of cells in which a link
failure occurs and that are indicated by the first part of content
changes, a total quantity of bits that need to be reported to
indicate whether a new link is identified for each cell in which
the link failure occurs also changes accordingly, that is, a
quantity of bits of the second part of content also changes.
Therefore, if the first part of content and the second part of
content are carried on different resources or independently
encoded, the network device may not allocate a fixed-size resource
based on a maximum quantity of bits, thereby reducing resource
overheads.
[0306] It should be understood that, in the case 2, the first
resource and the second resource may be a same resource; in this
case, the first part of content and the second part of content are
independently encoded. The first resource and the second resource
may alternatively be different resources.
[0307] Based on the foregoing implementation, the network device
may configure one or more resources for the terminal device. The
resource is used to carry the first indication information, and the
first indication information may indicate whether a link failure
occurs in one or more cells, or indicate a cell identifier of one
or more cells in which a link failure occurs, and indicate a new
link identification status of each of the one or more cells
(whether a new link is identified). The terminal device reports the
first indication information to the network device. If the network
device can learn of the cell in which the link failure occurs and
the new link identification status of the cell, the network device
may trigger a new reference signal resource set in time based on
the new link identification status of each cell in which the link
failure occurs, thereby reducing a link failure recovery delay. In
addition, when a link failure occurs in a plurality of cells, link
recovery can be simultaneously performed according to the method,
thereby reducing a link failure recovery delay.
[0308] In a possible implementation, the first indication
information includes a first part of content and a second part of
content, the first part of content is used to indicate an
identifier of one cell in which a link failure occurs, and the
second part of content is used to indicate whether a new link is
identified for the cell.
[0309] It should be understood that, in this implementation,
operation 302 is an optional operation.
[0310] Correspondingly, the network device may decode or parse the
first part of content and the second part of content according to
the method. That is, the second part of content is decoded or
parsed based on the first part of content.
[0311] In one embodiment, the second part of content indicates anew
link identification status (whether a new link is identified)
corresponding to the cell in which the link failure occurs and that
is indicated by the first part of content. Specifically, it is
assumed that the network device configures Q SCells (In one
embodiment, the Q SCells are SCells that require link failure
detection, that is, the network device configures the Q SCells that
require link failure detection). The terminal device determines
that a link failure occurs in one or more SCells. The terminal
device reports an identifier of one of three SCells in which the
link failure occurs to the network device, and reports a new link
identification status (information indicating whether a new link is
identified) of the SCell to the network device.
[0312] It should be understood that, in the foregoing
implementation, the first indication information may have a
plurality of forms. The following describes in detail the first
indication information in some possible cases, and describes
possible resource configuration manners of the first part of
content and the second part of content in this implementation. In
one embodiment, the first part of content and the second part of
content are carried on different resources, and/or the first part
of content and the second part of content are independently
encoded. The resource may be a PRACH resource (contention-based or
non-contention-based), a PUCCH resource, a semi-persistent PUSCH
resource, or the like.
Example 5
[0313] The network device configures a plurality of first resources
used to carry the first part of content, and one second resource
used to carry the second part of content. The terminal device may
report, in an implicit manner, an identifier of one first cell in
which a link failure occurs, and/or report a new link
identification status of the first cell in which the link failure
occurs. The terminal device selects one resource from the plurality
of first resources to send the first part of content (that is, the
identifier of the first cell in which the link failure occurs), and
sends, on the second resource, the new link identification status
(that is, the second part of content) of the first cell indicated
by the first part of content. More specifically, the network device
may configure P1 first resources used to carry the first part of
content, and one second resource used to carry the second part of
content, where P1.gtoreq.1, and P1 is an integer. The terminal
device may implicitly report, based on an association relationship
between resources or between a resource and a cell, an identifier
of one cell in which a link failure occurs, and report, based on
the identifier of the cell in which the link failure occurs and
that is indicated by the first part of content, a status of whether
a new link is identified for the cell in which the link failure
occurs. For example, the P1 first resources may be associated with
Q first cells. Further, P1=Q, and one of the P1 first resources may
be associated with one of the Q first cells (it may also be
understood that each of the Q first cells is associated with one
first resource). For example, the network device configures five
first resources corresponding to cells #1, #2, #3, #4, and #5, and
one second resource. The terminal determines that a link failure
occurs in the cell #2, reports a first part of content on the first
resource #2, and reports a new link identification status of the
cell #2 on the second resource.
[0314] For example, for a cell C1 in which a link failure occurs,
the first part of content carried on the first resource is used to
indicate an identifier C1 of the cell, and the second part of
content carried on the second resource is used to indicate that no
new link is identified for C1. Similarly, for a cell C2 in which a
link failure occurs, the network device also configures one first
resource for C2. The first part of content carried on the first
resource is used to indicate an identifier C2 of the cell, and the
second part of content carried on the second resource is used to
indicate that a new link is identified for C2.
Example 6
[0315] The network device configures one first resource used to
carry the first part of content, and one second resource used to
carry the second part of content. The terminal device may report,
in an explicit manner, an identifier (that is, the first part of
content) of one first cell in which a link failure occurs, and
report a new link identification status (that is, the second part
of content) of the first cell in which the link failure occurs. The
terminal device sends the first part of content on the first
resource, and sends the second part of content on the second
resource.
[0316] It should be understood that, in the foregoing
implementation, the first resource and the second resource may be a
same resource; in this case, the first part of content and the
second part of content are independently encoded, and each occupy
different bits. The first resource and the second resource may
alternatively be different resources.
[0317] Based on the foregoing implementation, the network device
may configure one or more resources for the terminal device, where
the resource is used to carry the first indication information. The
first indication information indicates an identifier of a cell in
which a link failure occurs, and information indicating whether a
new link is identified for the cell in which the link failure
occurs. The terminal device reports the first indication
information to the network device on a corresponding resource. If
the network device can learn of the cell in which the link failure
occurs and a new link identification status of the cell, the
network device may trigger a new resource set in time based on the
new link identification status of the cell in which the link
failure occurs, thereby reducing a link failure recovery delay. In
addition, the network device may configure one or more resources
used to indicate the identifier of the cell in which the link
failure occurs, and configure another resource used to indicate the
new link identification status of the cell in which the link
failure occurs. Alternatively, the terminal device may report, by
using some bits, the identifier of the cell in which the link
failure occurs, and then report, by using another bit, the new link
identification status of the cell in which the link failure occurs.
It may also be understood that the terminal device determines the
second part of content based on the reported first part of content.
The method can effectively reduce resource overheads.
[0318] In addition, when a link failure occurs in one cell, link
recovery may be separately performed for the cell according to the
method.
[0319] In a possible implementation, the first indication
information includes a first part of content and a second part of
content, the first part of content is used to indicate identifiers
of a plurality of cells in which a link failure occurs, and the
second part of content is used to indicate whether no new link is
identified for all of the plurality of cells in which the link
failure occurs.
[0320] It should be understood that, in this implementation,
operation 302 is an optional operation.
[0321] That the second part of content is used to indicate whether
no new link is identified for all of the plurality of cells in
which the link failure occurs may be understood as that the first
state is reported when no new link is identified for all of the
plurality of cells in which the link failure occurs and that are
indicated in the first part of content, and a second state is
reported when at least one new link is identified for the plurality
of cells in which the link failure occurs and that are indicated in
the first part of content.
[0322] It should be understood that, herein, the first state is a
state in which each of the M first cells has no first reference
signal that satisfies the first preset condition, and the second
state is a state in which a j.sup.th first cell in the M first
cells has a first reference signal that satisfies the first preset
condition, or the second state is a state in which at least one of
the M first cells has a first reference signal that satisfies the
first preset condition.
[0323] It should be further understood that, in this embodiment of
this application, the first state and the second state in the
second part of content may be indicated in the following three
manners.
[0324] Manner 1: Two state values are used. For example, a state
value 0 indicates the first state, and a state value 1 indicates
the second state.
[0325] Manner 2: Two resources are used. For example, a signal is
sent on one second resource to indicate the first state, and a
signal is sent on another second resource to indicate the second
state.
[0326] Manner 3: The two states are represented by sending or not
sending a signal on one second resource. For example, the first
state is represented by not sending a signal on the second
resource, and the second state is represented by sending a signal
on the second resource.
[0327] It should be understood that, in this embodiment of this
application, there are a scenario in which the second part of
content is sent and a scenario in which the second part of content
is not sent, and the foregoing three manners are all possible
implementations, and should not affect the solutions in this
application.
[0328] In addition, the first state in the first indication
information/the first request message, or a first state in second
indication information/a second request message may be further
indicated in a method 4.
[0329] Method 4: The first state is indicated by using a special
state value. As shown in the following Table 3, the indication
information includes two bits used to indicate information about a
reference signal, and a minimum state value (which may be a 00
state) of the two bits indicates the first state.
TABLE-US-00003 TABLE 3 Value (reference signal information)
Indicated reference signal 00 No beam (no new link) 01 Reference
signal #1 10 Reference signal #2 11 Reference signal #3
[0330] Specifically, it is assumed that the network device provides
Q SCells for the terminal device. The terminal device determines
that a link failure occurs in three SCells, and the terminal device
reports identifiers (identifications, IDs) of the three SCells in
which the link failure occurs to the network device. As shown in
the following Table 4, the identifiers of the three SCells in which
the link failure occurs are respectively C1, C2, and C3. The first
part of content may include the identifiers of the three cells in
which the link failure occurs, and the second part of content may
include information indicating whether no new link is identified
for all of the three cells. For example, no new link is identified
for all of C1, C2, and C3. Therefore, the second part of content is
yes, and is used to notify the network device that no new link is
identified for all of the three SCells in which the link failure
occurs.
TABLE-US-00004 TABLE 4 SCell identifier Whether no new link is
identified (first part of content) (second part of content) C1 Yes
C2 C3
[0331] It should be understood that, in the foregoing
implementation, the first indication information may have a
plurality of forms. The following describes in detail the first
indication information in some possible cases, and describes
possible resource configuration manners of the first part of
content and the second part of content in this implementation by
cases.
Example 7
[0332] The network device configures a plurality of first resources
used to carry the first part of content, and one second resource
used to carry the second part of content. The terminal device may
report, in an implicit manner, identifiers of a plurality of first
cells in which a link failure occurs, and/or report a status of
whether no corresponding new link is identified for all of the
plurality of first cells in which the link failure occurs. The
terminal device selects at least two resources from the plurality
of first resources to send the first part of content (that is, the
identifiers of the plurality of first cells in which the link
failure occurs), and sends, on the second resource, the status of
whether no new link is identified for all of the plurality of first
cells indicated by the first part of content (that is, the second
part of content).
[0333] More specifically, the network device may configure P1 first
resources used to carry the first part of content, and one second
resource used to carry the second part of content, where
P1.gtoreq.1, and P1 is an integer. The terminal device may
implicitly report, based on an association relationship between
resources or between a resource and a cell, identifiers of a
plurality of cells in which a link failure occurs, and report,
based on the identifiers of the plurality of cells in which the
link failure occurs and that are indicated by the first part of
content, a status of whether no new link is identified for all of
the plurality of cells in which the link failure occurs. For
example, the P1 first resources may be associated with Q first
cells. Further, P1=Q, and one of the P1 first resources may be
associated with one of the Q first cells (it may also be understood
that each of the Q first cells is associated with one first
resource). For example, the network device configures five first
resources corresponding to cells #1, #2, #3, #4, and #5, and one
second resource. The terminal determines that a link failure occurs
in the cell #2 and the cell #5, reports a first part of content on
the first resource #2 and the first resource #5, and reports new
link identification statuses of the cell #2 and the cell #5 on the
second resource (for example, if a new link of the cell #2 and a
new link of the cell #5 are not identified, the state value 0 is
reported on the second resource; or if at least one of a new link
of the cell #2 and a new link of the cell #5 is identified, the
state value 1 is reported on the second resource).
Example 8
[0334] The network device configures one first resource used to
carry the first part of content, and one second resource used to
carry the second part of content. The terminal device may report,
in an explicit manner, identifiers (that is, the first part of
content) of a plurality of first cells in which a link failure
occurs, and report a status of whether no new link is identified
for all of the plurality of first cells in which the link failure
occurs (that is, the second part of content). The terminal device
sends the first part of content on the first resource, and sends
the second part of content on the second resource. For example, the
network device configures one first resource (where the resource
may carry information of a plurality of bits) and one second
resource. The terminal determines that a link failure occurs in a
cell #2 and a cell #5, reports an identifier of the cell #2 and an
identifier of the cell #5 (that is, the first part of content) on
the first resource, and reports new link identification statuses of
the cell #2 and the cell #5 on the second resource. For example, a
total of 16 cells (cells #1 to 16) require link failure detection,
and 0001 and 0100 are reported on the first resource, where 0001
indicates a cell #2, and 0100 indicates a cell #5. If a new link of
the cell #2 and a new link of the cell #5 are not identified, the
state value 0 is reported on the second resource; or if at least
one of a new link of the cell #2 and a new link of the cell #5 is
identified, the state value 1 is reported on the second
resource.
[0335] It should be understood that, in the foregoing
implementation, the first resource and the second resource may be a
same resource; in this case, the first part of content and the
second part of content are independently encoded, and each occupy
different bits. The first resource and the second resource may
alternatively be different resources.
[0336] It should be understood that in the example 5 and the
example 7, the network device configures a corresponding first
resource for each SCell, where the first resource is used to carry
the first part of content (that is, indicating an identifier of one
or more cells in which a link failure occurs), and configures one
second resource to indicate whether no new link is identified for
all of the one or more cells in which the link failure occurs. The
terminal device may send the first part of content on one or more
first resources, to indicate that a link failure occurs in one or
more cells corresponding to the resource. After determining whether
no new link is identified for all of the one or more cells, the
terminal device sends the second part of content on the second
resource, or determines whether to send a signal on the second
resource configured by the network device.
[0337] It should be understood that in the example 6 and the
example 8, the network device configures one first resource, where
the first resource is used to carry the first part of content (that
is, indicating an identifier of one or more cells in which a link
failure occurs), and configures one second resource to indicate
whether no new link is identified for all of the one or more cells
in which the link failure occurs. The terminal device may send the
first part of content on one or more first resources, to indicate
that a link failure occurs in one or more cells corresponding to
the resource. After the terminal device determines whether no new
link is identified for all of the one or more cells, the terminal
device sends the second part of content on the second resource, or
determines whether to send a signal on the second resource
configured by the network device.
[0338] Based on the foregoing implementation, the network device
may configure one or more resources for the terminal device, where
the resource is used to carry the first part of content, the first
part of content may indicate an identifier of a cell in which a
link failure occurs; and configure one second resource for the cell
in which the link failure occurs, where the second resource is used
to carry the second part of content, and the second part of content
may indicate whether no new link is identified for the cell in
which the link failure occurs. In addition, the first indication
information including the first part of content and the second part
of content is reported to the network device. If the network device
can learn of a plurality of cells in which a link failure occurs
and a general new link identification status of the plurality of
cells, the network device may trigger a new resource set in time
based on the general new link identification status of the
plurality of cells in which the link failure occurs, thereby
reducing a link failure recovery delay.
[0339] In addition, compared with the foregoing technical solution
of configuring one second resource for each SCell, in this
implementation, one second resource is configured for a plurality
of SCells in which a link failure occurs, and indication
information indicating whether no new link is identified for all of
the SCells in which the link failure occurs is reported, thereby
reducing resource overheads. In other words, because a plurality of
cells in which a link failure occurs share one second resource for
indicating the second part of content, or because a plurality of
cells in which a link failure occurs share one bit for indicating
the second part of content, resource overheads can be effectively
reduced.
[0340] In one embodiment, the first resource and the second
resource may be physical uplink control channels (PUCCHs). In other
words, the first request message may be sent to the network device
through a PUCCH. This is not limited in this application.
[0341] In one embodiment, it should be understood that information
reported in the explicit manner in the example 1 to the example 8
is generally sent through a PUCCH channel or a PUSCH channel that
may carry information of a plurality of bits. In one embodiment, it
should be understood that information reported in the implicit
manner in the example 1 to the example 8 is generally carried and
sent through a PRACH channel, a PUCCH channel, or some sequences
that may carry information of one bit (better reliability can be
obtained and transmission accuracy can be improved), or may be sent
by using different time domain/frequency domain/code domain
resources of a PRACH/PUCCH/PUSCH.
[0342] 304: The network device determines, based on the first
request information or the first indication information, the cell
in which the link failure occurs and/or the new link identification
status of the cell in which the link failure occurs, and generates
downlink control information (downlink control information,
DCI).
[0343] In other words, the network device determines, based on the
first request information, the cell in which the link failure
occurs and/or the new link identification status of the cell in
which the link failure occurs, and generates a response message of
the first request message.
[0344] In other words, the network device generates the response
message of the first request message based on the first request
information.
[0345] It should be understood that, the response message of the
first request message may be the downlink control information.
[0346] In one embodiment, the response message of the first request
message may be used to indicate a PUSCH resource.
[0347] In one embodiment, the first request message indicates the
first state, and the DCI is used to indicate a second reference
signal resource set.
[0348] Specifically, the terminal device determines that there is
no new link, and reports the identifier of the first cell in which
the link failure occurs to the network device. The network device
may reconfigure another reference signal resource set for the
terminal device, that is, reconfigure the second reference signal
resource set for the terminal device by using the DCI.
[0349] In one embodiment, the second reference signal resource set
may include a periodic reference signal, an aperiodic reference
signal, or a semi-periodic reference signal. This is not limited in
this application.
[0350] It should be understood that, the "second reference signal
resource set" in this application may include a reference signal
resource of the first cell, or may include only a reference signal
resource of another cell, or may include a reference signal of the
first cell and a reference signal resource of the another cell (in
other words, the second reference signal resource set may include
reference signal resources of a plurality of cells). This is not
limited in this embodiment of this application.
[0351] It should be understood that, in this application, the
second reference signal resource set may be one resource set, or
may be a plurality of reference signal resource sets.
[0352] In one embodiment, if the first indication information
indicates the first state, the DCI indicates the second reference
signal resource set, or the DCI is associated with the second
reference signal resource set by default. If the first indication
information indicates the second state, the DCI is associated with
a first reference signal resource set by default. In one
embodiment, the terminal device sends the second request message on
a resource indicated by the DCI.
[0353] In one embodiment, the second reference signal resource set
may not include a candidate beam list (candidate beam list). In
operation 302, when a candidate beam list is configured, the
terminal device has detected a reference signal in the candidate
beam list, and determines that no new link is identified.
Therefore, the second reference signal resource set does not
include a resource in the candidate beam list, so that the terminal
device can be prevented from performing detection again, thereby
reducing a link recovery delay.
[0354] In one embodiment, the DCI is sent on a resource in a search
space set (beam failure recovery search space, BFR search space)
and/or a control resource set (CORESET) used to send a
communication failure recovery response.
[0355] In the foregoing solution, in a process of sending the DCI,
the DCI is sent in the search space set and/or the control resource
set used by the network device to send the BFRR, and a link
recovery process may be continued through a retransmission
operation, thereby improving link recovery reliability.
[0356] In one embodiment, the DCI is scrambled by using a link
failure recovery request-radio network temporary identifier (beam
failure recovery-radio network temporary identifier, BFR-RNTI).
[0357] In the foregoing solution, the DCI sent by the network
device to the terminal device is scrambled by using the BFR-RNTI.
After receiving the scrambled DCI, the terminal device may
determine, based on the scrambled information, that the DCI is used
in the link recovery process, so that a detection process of the
terminal device is simplified, thereby reducing a link recovery
delay and improving link recovery reliability.
[0358] In one embodiment, the DCI may be scrambled by using a cell
radio network temporary identifier (cell radio network temporary
identifier, C-RNTI), or scrambled by using another dedicated radio
network temporary identifier RNTI. This is not limited in this
embodiment of this application.
[0359] It should be understood that, in this operation, the "second
resource" that carries the response message of the first request
message is different from the "second resource" in operation
303.
[0360] 305: The network device sends the DCI to the terminal
device, and correspondingly, the terminal device receives the DCI
sent by the network device. It should be understood that operation
304 and operation 305 may be a same operation.
[0361] 306: The terminal device determines the second reference
signal resource set based on the DCI sent by the network device,
and identifies new link information in the second reference signal
resource set.
[0362] Specifically, the terminal device receives the DCI sent by
the network device, and the terminal device identifies a new link
in the second reference signal resource set indicated by the
DCI.
[0363] For example, in a process in which the terminal device
identifies a new link, when the terminal device determines that
there is a reference signal, in the second reference signal
resource set, whose channel quality information is greater than or
equal to the second preset threshold, the terminal device may
determine, as a new link, the reference signal whose channel
quality information is greater than or equal to the second preset
threshold.
[0364] In one embodiment, the second preset threshold herein may be
a link recovery threshold, or may be a reconfigured threshold. This
is not limited in this application.
[0365] It should be understood that, the second preset threshold
may be the first preset threshold.
[0366] 307: The terminal device sends the second request message to
the network device, and correspondingly, the network device
receives the second request message sent by the terminal device,
where the second request message includes second indication
information, and the second indication information is used to
indicate a state of a new link identified by the terminal
device.
[0367] In one embodiment, the second request message may be a
second link failure request message (BFRQ 2).
[0368] In one embodiment, in operation 306, the terminal device
determines the new link from the second reference signal resource
set, and when the channel quality information of the new link is
greater than or equal to the second preset threshold, the second
indication information may include the information about the new
link identified by the terminal device, and is reported to the
network device by using the second link failure request message
(BFRQ 2).
[0369] For example, content of the second indication information
may be shown in the following Table 5. A value of two bits is used
to indicate an identifier of an SCell in which a link failure
occurs, and each SCell in which the link failure occurs corresponds
to information about an identified new link, such as a beam 0 or a
beam 1.
TABLE-US-00005 TABLE 5 Value (SCell identifier) Information about
an identified new link 00 Beam 0 10 Beam 2
[0370] In one embodiment, the information about the new link
reported in the second indication information is sequentially
sorted in ascending order of the IDs of the SCells indicated in the
first indication information.
[0371] For example, as shown in the following Table 6, a sequence
obtained through sorting based on the IDs of the SCells reported in
the first indication information is: C1, C2, and C3, and identified
beams are also sorted in an order of the SCell IDs. To be specific,
an identifier or value information of an SCell does not need to be
reported, and only information about a beam 0, a beam 1, and a beam
2 needs to be reported. The network device may also accurately
learn of a new link corresponding to an SCell in which a link
failure occurs. This method can reduce resource overheads.
TABLE-US-00006 TABLE 6 Value (SCell identifier) Information about
an identified new link C1 Beam 0 C2 Beam 1 C3 Beam 2
[0372] In another embodiment, in operation 306, when the terminal
device determines, from the second reference signal resource set,
that no new link satisfies a condition, that is, channel quality
information of all links in the second reference signal resource
set is less than the second preset threshold, the second indication
information is used to indicate that there is no new link (no new
beam state), and is reported to the network device by using the
second link failure request message (BFRQ 2). Then, operations 304,
305, and 306 are cyclically performed until the terminal device
identifies a new link.
[0373] For example, in this case, content of the second indication
information may be shown in the following Table 7. A value (value)
of two bits is used to indicate an identifier of an SCell in which
a link failure occurs. When no new link is identified for an SCell
in which a link failure occurs, indication information of no beam
is reported, to indicate that there is no new link.
TABLE-US-00007 TABLE 7 Value (SCell identifier) Information about
an identified new link 00 No beam
[0374] It should be understood that, in a process in which the
terminal device cyclically performs operations 304, 305, and 306 to
identify a new link, monitoring may be performed by using a link
failure recovery timer (beam failure recovery timer) and a link
failure recovery counter (beam failure recovery counter).
Specifically, when the terminal device determines that a quantity
of no new beam states is greater than or equal to a maximum value
of the link failure recovery counter, and still does not receive
the BFRR, it may be considered that the link recovery fails.
Alternatively, when duration in which the terminal device starts
link recovery is longer than or equal to a time length of recovery
of the recovery timer, it may be considered that the link recovery
fails, and sending of the link failure recovery request message
(BFRQ) is stopped and/or timing of the link failure recovery timer
and counting of the link failure recovery counter are
recovered.
[0375] Alternatively, in operation 306, when the terminal device
determines, from the second reference signal resource set, that no
new link satisfies a condition, that is, channel quality
information of all links in the second reference signal resource
set is less than the second preset threshold, the second indication
information is used to indicate at least one first reference
signal, and is reported to the network device by using the second
link failure request message (BFRQ 2).
[0376] Alternatively, in operation 306, when the terminal device
determines, from the second reference signal resource set, that no
new link satisfies a condition, that is, channel quality
information of all links in the second reference signal resource
set is less than the second preset threshold, the second indication
information is used to indicate at least one second reference
signal, and is reported to the network device by using the second
link failure request message (BFRQ 2).
[0377] Alternatively, in operation 306, when the terminal device
determines, from the first reference signal resource set, that no
new link satisfies a condition, that is, channel quality
information of all links in the first reference signal resource set
is less than the first preset threshold, the second indication
information is used to indicate at least one second reference
signal, and is reported to the network device by using the second
link failure request message (BFRQ 2).
[0378] It should be understood that, herein, when the network
device does not configure the link recovery threshold for the
SCell, and the terminal device detects no new link in the second
reference signal resource set, the terminal device may report the
at least one first reference signal by using the second indication
information. The at least one reported first reference signal is a
reference signal with relatively good channel quality in an
original set. In this case, the channel quality of the at least one
reported first reference signal may be greater than, equal to, or
less than the second preset threshold. This is not limited in this
application.
[0379] In one embodiment, content included in the first request
message in operation 303 and content included in the second request
message in operation 307 are independently encoded.
[0380] In another embodiment, the first request message in
operation 303 and the second request message in operation 307 may
be a same request message or different request messages. In other
words, the first indication information and the second indication
information may be sent to the network device by using a same
request message, or sent to the network device by using different
request messages.
[0381] In another embodiment, the first request message in
operation 303 and the second request message in operation 307 may
be sent by using a same channel, or sent by using different
channels. This is not limited in this application.
[0382] For example, the terminal device may send the first request
message to the network device by using the first resource, receive,
by using the second resource, the DCI sent by the network device,
and receive a response message of the second request message on a
third resource. In one embodiment, the first resource may be a
physical uplink shared channel (PUSCH). This is not limited in this
application.
[0383] It should be understood that, the "second resource" in this
operation may be different from the "second resource" in operation
303.
[0384] In another embodiment, if the first indication information
indicates the first state, the terminal device reports information
about K second reference signals in the second reference signal
resource set on a preset fourth resource, where the second
reference signal resource set is a default resource set or a preset
resource set. If the first indication information indicates the
second state, the terminal device reports information about K first
reference signals in the first reference signal resource set on a
preset fourth resource. It should be understood that, the preset
fourth resource may be a resource associated with the first
resource and/or the second resource. Configuration information of
the fourth resource is configured by using one or a combination of
a broadcast channel, a system message, an updated system message,
layer 1 signaling (DCI), and higher layer signaling (for example,
RRC or a MAC-CE). Alternatively, an association relationship
between the fourth resource and the first resource/second resource
may be configured by using one or a combination of a broadcast
channel, a system message, an updated system message, layer 1
signaling (DCI), and higher layer signaling (radio resource control
(RRC) signaling or media access control-control element (medium
access control-control element, MAC-CE) signaling). In one
embodiment, in this implementation, operation 304/305/306 may not
be performed.
[0385] In one embodiment, when the first indication information is
used to indicate that the terminal device identifies no new link,
the terminal device does not generate the second indication
information or send the second indication information, but waits
for QCL that is sent by the network device and that is used to
reconfigure a resource set, to perform link recovery. In this way,
a recovery probability can be increased after a link failure.
Otherwise, when the first indication information indicates that the
terminal device identifies a new link, the terminal device
generates the second indication information, sends the second
indication information, and reports the identified new link to the
network device.
[0386] In another embodiment, when the first indication information
indicates that the terminal device identifies no new link, the
reference signal indicated by the second indication information may
be an aperiodic/periodic/semi-periodic reference signal in a
reference signal resource set (a second reference signal resource
set) or the like, or a default reference signal resource set (for
example, a reference signal resource set used for beam management
BM, a reference signal resource set used for RRM measurement, or a
reference signal resource set that uses another function).
Otherwise, when the first indication information indicates that the
terminal device identifies a new link, the reference signal
corresponding to the second indication information is a
corresponding reference signal in the candidate beam list.
[0387] 308: The network device determines information about the new
link based on the second indication information or the second
request message.
[0388] 309: The network device sends a link failure recovery
response message (BFRR) to the terminal device, and
correspondingly, the terminal device receives the link failure
recovery response message (BFRR).
[0389] 310: The terminal device detects the link failure recovery
response message (BFRR), and determines that the link recovery
succeeds.
[0390] Specifically, the terminal device detects the BFRR based on
the information about the new link included in the second
indication information that is fed back in operation 307. If the
terminal device detects BFRR, it is considered that the link
failure recovery succeeds. If the terminal device detects no BFRR,
the terminal device may perform the process of operations 303 to
307 again until the link failure recovery succeeds.
[0391] It should be understood that, in a process in which the
terminal device may perform operations 303 to 307 again, monitoring
may be performed by using the link failure recovery timer (beam
failure recovery timer) and the link failure recovery counter (beam
failure recovery counter). Specifically, when a quantity of times
that the terminal device sends the link failure recovery request is
greater than or equal to the maximum value of the link failure
recovery counter, or a time length for link failure recovery
exceeds preset duration, it is considered that the link failure
recovery fails.
[0392] It should be noted that, in the embodiments of this
application, the "cell identifier" may alternatively be replaced
with a "cell index". Reference signal information may include a
reference signal index/an index of an SSB and/or reference signal
quality/quality of the SSB.
[0393] Based on the foregoing solution, when a link failure occurs
and link recovery is performed, if the terminal device determines
that no new link is identified, the terminal device may report, to
the network device, an identifier of a cell in which the link
failure occurs and/or information indicating whether a new link is
identified for each cell. The network device may reconfigure a new
resource set based on the information, and notify the terminal
device of the new resource set by using downlink control
information. In other words, a reference signal in another resource
set is triggered by using the DCI, and the reference signal in the
resource set is reported for link recovery. In this way, a link
failure recovery probability can be increased, a link failure
recovery delay can be reduced, and link failure recovery
reliability can be improved.
[0394] It should be understood that, the link failure recovery
process may include all or some of the operations described above.
This is not limited in this application. For example, a
communications system may perform operations 301, 303, 304, 305,
306, and 307, but does not perform operation 302. Alternatively,
operations 301 and 303 may be performed, but intermediate
operations may not be performed, or subsequent operations may not
be performed. Alternatively, operations 301, 303, and 307 may be
performed, but intermediate operations are not performed.
Alternatively, one or more of the foregoing operations may be
performed, or all the operations are performed.
[0395] It should be noted that, after determining that there is no
new link in operation 302, the terminal device may detect DCI
information in the second cell, to determine a new reference signal
resource set. After determining that there is a new link, the
terminal device may detect response information in the first cell
based on the new link.
[0396] FIG. 4 is a schematic flowchart of another example of a link
failure recovery method according to an embodiment of this
application. An example in which a link between an SCell and a
terminal device fails is used, and each operation of the method 400
is described in detail by using the terminal device and a network
device as execution bodies.
[0397] By way of example, and not limitation, the method 400 may
alternatively be performed by a chip used in the terminal device
and a chip used in the network device. This is not limited in this
application.
[0398] 401: The terminal device detects a working state of a
current link. For example, the terminal device may detect the
current link, and determine that the current link fails.
[0399] 402: The terminal device determines that there is no new
link.
[0400] 403: The terminal device sends a first request message to
the network device, and correspondingly, the network device
receives the first request message sent by the terminal device,
where the first request message includes first indication
information, and the first indication information is used to
indicate that the terminal device has no new link.
[0401] 404: The network device determines, based on the first
indication information, a cell in which a link failure occurs and a
new link identification status of the cell.
[0402] It should be understood that, for the foregoing operations
401 to 404, refer to operations 301 to 304 in the method 300. For
brevity, details are not described herein again.
[0403] 405: The network device sends a transmission configuration
indicator (transmission configuration indicator, TCI) to the
terminal device, and correspondingly, the terminal device receives
the TCI sent by the network device.
[0404] Specifically, when the network device determines that M
SCells are in a state in which no new link is identified, the
terminal device does not detect link failure recovery response
information (BFRR), but waits for TCI reconfiguration signaling. If
the TCI reconfiguration signaling is received, it may be considered
that link failure recovery succeeds, and timing of a link failure
recovery clock is stopped.
[0405] Alternatively, if the terminal device receives TCI
reconfiguration signaling before a link failure recovery clock
expires, and the terminal device receives the information, timing
of the link failure recovery clock is stopped; otherwise, if a time
length for link failure recovery exceeds preset duration, it is
considered that the link failure recovery fails.
[0406] Based on the foregoing technical solution, after it is
determined that no new link is identified for the cell in which the
link failure occurs, the terminal device does not need to detect
the link failure recovery response information, but waits for the
TCI reconfiguration signaling with low power consumption, so that
power can be saved.
[0407] It should be noted that, in the embodiments of this
application, the first cell may be an SCell, and the second cell
may be a PCell or an SCell having an uplink resource.
[0408] The foregoing describes in detail the link failure recovery
method in the embodiments of this application with reference to
FIG. 3 and FIG. 4. The following describes in detail link failure
recovery apparatuses in the embodiments of this application with
reference to FIG. 5 to FIG. 8.
[0409] FIG. 5 is a schematic block diagram of a link failure
recovery apparatus 500 according to an embodiment of this
application. The apparatus 500 may correspond to the terminal
device described in the method 300 and the method 400, or may be a
chip or a component used in the terminal device. In addition,
modules or units in the apparatus 500 are respectively configured
to perform actions or processing processes performed by the
terminal device in the method 300 and the method 400. As shown in
FIG. 5, the communications apparatus 500 may include a processing
unit 510 and a communications unit 520.
[0410] The processing unit 510 is configured to determine that M
first cells in which a link failure occurs is in a first state,
where the first state is a state in which each of the M first cells
has no first reference signal that satisfies a first preset
condition, M.gtoreq.1, and M is an integer.
[0411] The communications unit 520 is configured to send a first
request message on a first resource, where the first request
message is used to indicate cell information of the M first
cells.
[0412] The communications unit 520 is further configured to receive
a response message of the first request message on a second
resource, where the response message of the first request message
is used to indicate a second reference signal resource set, the
second reference signal resource set includes resources of N second
reference signals used to recover the M first cells, N.gtoreq.1,
and N is an integer.
[0413] The processing unit 510 is further configured to determine
the second reference signal resource set based on the response
message of the first request message.
[0414] Specifically, the processing unit 510 is configured to
perform 301, 302, and 306 in the method 300 and 401, 402, and 406
in the method 400. The communications unit 520 is configured to
perform 303, 305, 307, and 309 in the method 300 and 403 and 405 in
the method 400. A specific process in which each unit performs the
foregoing corresponding operation is described in detail in the
method 400. For brevity, details are not described herein
again.
[0415] FIG. 6 is a schematic block diagram of a link failure
recovery apparatus 600 according to an embodiment of this
application. The apparatus 600 may correspond to (for example, may
be applied to or may be) the base station described in the method
300 and the method 400. In addition, modules or units in the
apparatus 600 are respectively configured to perform actions or
processing processes performed by the base station in the method
300 and the method 400. As shown in FIG. 6, the communications
apparatus 600 may include a processing unit 610 and a
communications unit 620.
[0416] The communications unit 620 is configured to receive a first
request message on a first resource, where the first request
message is used to indicate cell information of M first cells in
which a link failure occurs, the M first cells are in a first
state, the first state is a state in which each of the M first
cells has no first reference signal that satisfies a first preset
condition, M.gtoreq.1, and M is an integer.
[0417] The processing unit 610 is configured to determine the cell
information of the M first cells based on the first request
message.
[0418] The communications unit 620 is further configured to send a
response message of the first request message on a second resource,
where the response message of the first request message is used to
indicate a second reference signal resource set, the second
reference signal resource set includes resources of N second
reference signals used to recover the M first cells, N.gtoreq.1,
and N is an integer.
[0419] Specifically, the processing unit 610 is configured to
perform 304 and 308 in the method 300 and 404 in the method 400.
The communications unit 620 is configured to perform 303, 305, 307,
and 309 in the method 300 and 403 and 405 in the method 400. A
specific process in which each unit performs the foregoing
corresponding operation is described in detail in the method 300
and the method 400. For brevity, details are not described herein
again.
[0420] FIG. 7 is a schematic diagram of a structure of a terminal
device 700 according to an embodiment of this application. As shown
in FIG. 7, the terminal device 700 includes a processor 710 and a
transceiver 720. In one embodiment, the terminal device 700 further
includes a memory 730. The processor 710, the transceiver 720, and
the memory 730 communicate with each other through an internal
connection path, to transfer a control signal and/or a data signal.
The memory 730 is configured to store a computer program. The
processor 710 is configured to invoke the computer program from the
memory 730 and run the computer program, to control the transceiver
720 to send and receive a signal.
[0421] The processor 710 and the memory 730 may be integrated into
one processing apparatus. The processor 710 is configured to
execute program code stored in the memory 730 to implement the
function of the terminal device in the foregoing method
embodiments. During specific implementation, the memory 730 may
alternatively be integrated into the processor 710, or may be
independent of the processor 710. The transceiver 720 may be
implemented by using a transceiver circuit.
[0422] The terminal device may further include an antenna 740,
configured to send, by using a radio signal, uplink data or uplink
control signaling output by the transceiver 720, or send, after
receiving downlink data or downlink control signaling, the downlink
data or the downlink control signaling to the transceiver 720 for
further processing.
[0423] It should be understood that, the apparatus 700 may
correspond to the terminal device in the method 300 and the method
400 according to the embodiments of this application, and the
apparatus 700 may alternatively be a chip or a component used in
the terminal device. In addition, modules in the apparatus 700
implement corresponding procedures in the method 300 in FIG. 3 and
the method 400 in FIG. 4. Specifically, the memory 730 is
configured to store program code, so that when the processor 710
executes the program code, the processor 710 is controlled to
perform 301, 302, and 306 in the method 300 and 401, 402, and 406
in the method 400. The transceiver 720 is configured to perform
303, 305, 307, and 309 in the method 300 and 403 and 405 in the
method 400. A specific process in which each unit performs the
foregoing corresponding operation is described in detail in the
method 400. For brevity, details are not described herein
again.
[0424] FIG. 8 is a schematic diagram of a structure of a network
device 800 according to an embodiment of this application. As shown
in FIG. 8, the network device 800 (for example, a base station)
includes a processor 810 and a transceiver 820. In one embodiment,
the network device 800 further includes a memory 830. The processor
810, the transceiver 820, and the memory 830 communicate with each
other through an internal connection path, to transfer a control
signal and/or a data signal. The memory 830 is configured to store
a computer program. The processor 810 is configured to invoke the
computer program from the memory 830 and run the computer program,
to control the transceiver 820 to send and receive a signal.
[0425] The processor 810 and the memory 830 may be integrated into
one processing apparatus. The processor 810 is configured to
execute program code stored in the memory 830 to implement the
function of the base station in the foregoing method embodiments.
During specific implementation, the memory 830 may alternatively be
integrated into the processor 810, or may be independent of the
processor 810. The transceiver 820 may be implemented by using a
transceiver circuit.
[0426] The network device may further include an antenna 840,
configured to send, by using a radio signal, downlink data or
downlink control signaling output by the transceiver 820, or send,
after receiving uplink data or uplink control signaling, the uplink
data or the uplink control signaling to the transceiver 820 for
further processing.
[0427] It should be understood that, the apparatus 800 may
correspond to the base station in the method 300 and the method 400
according to the embodiments of this application, and the apparatus
800 may alternatively be a chip or a component used in the base
station. In addition, modules in the apparatus 800 implement
corresponding procedures in the method 300 in FIG. 3 and the method
400 in FIG. 4. Specifically, the memory 830 is configured to store
program code, so that when the processor 810 executes the program
code, the processor 810 is controlled to perform 304 and 308 in the
method 300 and 404 in the method 400. The transceiver 820 is
configured to perform 303, 305, 307, and 309 in the method 300 and
403 and 405 in the method 400. A specific process in which each
unit performs the foregoing corresponding operation is described in
detail in the method 400. For brevity, details are not described
herein again.
[0428] It should be understood that, in the embodiments of this
application, the first request message and the second request
message may be same request information, for example, are
collectively referred to as the first request message. In this
case, "not sending the second request message" may be understood as
"not sending the second indication information"; or may be
understood as that the first request message does not include the
second indication information; or may be understood as that the
first request message includes only the first indication
information.
[0429] A person of ordinary skill in the art may be aware that, in
combination with the examples described in the embodiments
disclosed in this specification, units and algorithm operations may
be implemented by electronic hardware or a combination of computer
software and electronic hardware. Whether the functions are
performed by hardware or software depends on particular
applications and design constraint conditions of the technical
solutions. A person skilled in the art may use different methods to
implement the described functions for each particular application,
but it should not be considered that the implementation goes beyond
the scope of this application.
[0430] It may be clearly understood by a person skilled in the art
that, for the purpose of convenient and brief description, for a
detailed working process of the foregoing system, apparatus, and
unit, refer to a corresponding process in the foregoing method
embodiments. Details are not described herein again.
[0431] In the several embodiments provided in this application, it
should be understood that the disclosed system, apparatus, and
method may be implemented in other manners. For example, the
described apparatus embodiment is merely an example. Division into
the units is merely logical function division and may be other
division during actual implementation. For example, a plurality of
units or components may be combined. In addition, the displayed or
discussed mutual couplings or communication connections may be
indirect couplings or communication connections through some
interfaces, apparatuses, or units.
[0432] In addition, functional units in the embodiments of this
application may be integrated into one physical entity, or each of
the units corresponds to one physical entity, or two or more units
are integrated into one physical entity.
[0433] When the functions are implemented in the form of a software
functional unit and sold or used as an independent product, the
functions may be stored in a computer-readable storage medium.
Based on such an understanding, the technical solutions of this
application essentially, or the part contributing to the
conventional technology, or some of the technical solutions may be
implemented in a form of a software product. The computer software
product is stored in a storage medium, and includes several
instructions for instructing a computer device (which may be a
personal computer, a server, a network device, or the like) to
perform all or some of the operations of the methods described in
the embodiments of this application. The foregoing storage medium
includes: any medium that can store program code, such as a USB
flash drive, a removable hard disk, a read-only memory (ROM), a
random access memory (RAM), a magnetic disk, or an optical
disc.
* * * * *